Jochen Hoetzel - Academia.edu (original) (raw)
Papers by Jochen Hoetzel
L'invention concerne un procede pour fabriquer une cellule solaire p-i-n solaire a base de si... more L'invention concerne un procede pour fabriquer une cellule solaire p-i-n solaire a base de silicium amorphe. La cellule comprend un revetement antireflechissant et des contacts avant et arriere ZnO dope par LPCVD, lesdits contacts avant et arriere ZnO dope par LPCVD etant des films polycrystallins constitues de gros grains dont les extremites apparaissent au niveau de la surface de croissance sous forme de pyramides. Le procede consiste : a deposer ledit contact avant par un procede de depot chimique en phase vapeur sous pression reduite (LPCVD); a deposer les couches de silicium sur ladite cellule p-i-n solaire par depot chimique en phase vapeur active par plasma; a deposer ledit contact arriere par LPCVD; et a disposer le revetement antireflechissant. La cellule p-i-n solaire a base de silicium amorphe peut atteindre une efficacite stabilisee de 10,09 %.
... Click to zoom in 2 pages available to preview. Available from www.eupvsec-proceedings.com. ..... more ... Click to zoom in 2 pages available to preview. Available from www.eupvsec-proceedings.com. ... as front TCO The ZnO layers presented in this work (namely type-A and type-B) were modified compared to the layers used in a previous work presented at the 23rd EU PVSEC [7]. In ...
L'invention concerne un procede de fabrication d'une cellule tandem micromorphe. La cellu... more L'invention concerne un procede de fabrication d'une cellule tandem micromorphe. La cellule tandem micromorphe comprend une cellule de base μc-Si:H et une cellule superieure a-Si:H, une couche avant de contact LPCVD en ZnO et une couche arriere de contact en ZnO en combinaison avec un reflecteur blanc. Le procede comprend les etapes qui consistent a appliquer un concept AR - Anti-Reflechissant - sur la cellule tandem micromorphe et a implementer un reflecteur intermediaire dans la cellule tandem micromorphe. La cellule tandem micromorphe permet d'obtenir un rendement stabilise de 10,6 %.
Solar Energy Materials and Solar Cells, 2016
The influence of working pressure and inter-electrode gap distance on the quality of microcrystal... more The influence of working pressure and inter-electrode gap distance on the quality of microcrystalline silicon prepared by PECVD at 40 MHz in three different KAI™ reactors designs with inter-electrode gaps of 28 mm, 16 mm and 7 mm has been investigated. The microcrystalline devices were implemented and studied as bottom cells in MICROMORPH™ tandem modules or processed with an optical filter to simulate the absorption of a top cell on a module size of 1.43 m 2. Increasing the working pressure from 250 Pa to 2000 Pa resulted in an improvement of the efficiency of 1% absolute due to improvement in the open circuit voltage V oc and the fill factor FF. The influence of the deposition rate on the quality of the intrinsic absorber layers has been investigated and optimized. An unconventional crystallinity profile throughout the intrinsic absorber layer has been developed to further improve either the current density J sc or V oc and FF. By controlling and tuning the Raman crystallinity a very high open circuit voltage V oc of 41.42 V in a tandem cell design in full size modules (1.43 m 2) could be realized.
The 13th International Conference on Solid-State Sensors, Actuators and Microsystems, 2005. Digest of Technical Papers. TRANSDUCERS '05.
We present a process flow and characterization for the growth of freestanding carbon nanotubes on... more We present a process flow and characterization for the growth of freestanding carbon nanotubes on a polysihcon microelectromechanical device. Individual or multiple tubes can be directly grown bctween movable posts and electrically connected. The process is characterized to the point where minimum feature sizes of catalytic islands are determined as a function of the catalytic solution concentration. We show scanning electron microscopy pictures that validate the direct growth of nanotubes. The reported technology is batch-fabrication compatible as opposed to discrete fabrication processes and is opening the way to the synthesis and evaluation of mechanical nano-scale transduccrs based on carbon nanotubes. microscope (AFM) to apply a force on a suspended CNT while measuring the electric conductivity [6,7]. We suggest the usage of microsystem technology as a flexible platform for system design to mechanically deform and electrically sense CNTs in various ways (axial & torsional strain, bending, resonance) [8], given that the CNTs can be accurately integrated. Schematically shown in Fig. 1 is a proposed MEMS based test stand. bridgedCNT
Solar Energy Materials and Solar Cells, 2015
Light management is fundamental for achieving high performance thin-film silicon solar cells. We ... more Light management is fundamental for achieving high performance thin-film silicon solar cells. We highlight important developments of light management for record modules subdivided into several main categories: (a) reduction of reflection at interfaces by introducing antireflective layers; (b) reduction of parasitic losses in transparent conductive oxide layers; (c) improvement of light scattering combined with transparent conductive oxide surface morphology optimization; and (d) balancing of top cell and bottom cell currents by reflective layers. Specific aspects related to industrial production of large area modules are discussed including transparency/conductivity trade-offs, optimized deposition rates and coating uniformities.
In September 2010 the PEPPER project started after receiving a grant under the Framework Programm... more In September 2010 the PEPPER project started after receiving a grant under the Framework Programme FP7 for research of the European Union, coordinated by the DG Energy of the European Commission (no. 249782). The PEPPER project tackles major factors relating to micromorph module efficiency and production cost by assessing the influences of glass, TCO and silicon deposition (including in-situ cleaning). The project bridges the gap between research and industrial application by executing new developments and improvements in the field of TCO and PECVD reactors and processes and transferring them to production plants where the full impact on module efficiency and costs can be evaluated. The joint goal of this project is the demonstration of a 157Wp (stable) micromorph module with a cost of ownership (CoO) of 0.5€/Wp. Succeeding in this project will ensure the competitiveness of the Micromorph technology and further approach the final goal of grid parity. The first results of the project...
Diese Arbeit leistet einen Beitrag zur Kostenreduzierung bei der Herstellung von Si-Solarzellen d... more Diese Arbeit leistet einen Beitrag zur Kostenreduzierung bei der Herstellung von Si-Solarzellen durch die Anwendung einer speziellen LPE-Technologie auf UMG Si-Substraten. Dadurch wurde der Einsatz von EG-Si bei der LPE-Solarzellenherstellung erstmals völlig überflüssig. Eine neue, industriell kompatible Siebdrucktechnologie ermöglichte die Realisierung von kostengünstigen und effizienten Solarzellen.Hochwertige Si-Schichten wurden mit einer horizontalen LPE-Anlage auf unterschiedlichen Si-Substraten abgeschieden. Die Verwendung von UMG-Si als Substrat gelang, da die Diffusion von Verunreinigungen aus dem Substrat in die LPE-Schicht unterhalb der SIMS-Nachweisgrenze lag. Mit Hall-Messungen wurden LPE-Schichten mit unterschiedlichen Herstellungsparametern charakterisiert und optimiert. Durch chemisches Ätzen gelang die optische Auflösung von LPE-Schicht, UMG-Substrat und deren Übergang. Aus der LBIC-Analyse und PC1D-Simulation wurde die optimale LPE-Schichtdicke berechnet.Die Abschei...
A stabilized record efficiency of 9.1 % for an a-Si:H p-i-n test cell (1 cm2) could be obtained t... more A stabilized record efficiency of 9.1 % for an a-Si:H p-i-n test cell (1 cm2) could be obtained thanks to the enhanced light-trapping properties of LPCVD ZnO as front TCO and a rigorous process optimisation. ESTI of JRC independently confirms a stabilized aperture efficiency of 8.32 % for a mini-module based on a-Si:H p-i-n with ZnO as front TCO. 1.4 m2 large-area amorphous silicon p-i-n modules with 123 W initial power have been fabricated implementing such ZnO layers as front TCO. Micromorph test cells with initial efficiencies of 12.1 % have been prepared in the KAI-M reactor. Up-scaling of Micromorph tandems to mini-modules and 1.4 m2 area modules have led to remarkable high efficiencies. First results applying in-situ deposited intermediate reflector layers in the KAI-M PECVD system reveal promising results for next generation of Micromorph tandem devices.
2011 37th IEEE Photovoltaic Specialists Conference, 2011
ABSTRACT This work reports on the optimization of amorphous-microcrystalline silicon tandem solar... more ABSTRACT This work reports on the optimization of amorphous-microcrystalline silicon tandem solar cells and modules on LPCVD ZnO on 1.4m2 substrate size. The focus is on the optimization of PECVD deposition of n-and p-type doped layers for the microcrystalline silicon bottom cell deposited in a commercially available Oerlikon Solar KAI PECVD system. For this type of layers, both electro-optical properties with respect to cell and module efficiency as well as deposition rate with respect to throughput are of interest. A novel silicon oxide based n-layer which enhances current density of the solar cell by reducing absorption loss was introduced in the bottom cell design. An appropriate optimization of the n-layer was found crucial to achieve a suitable device performance. In a second step, the increase of the deposition rate of the n-and p-layers was addressed to match the throughput requirements for an industrial low cost production process.
Conference Record of the IEEE Photovoltaic Specialists Conference, 2011
In the first step, silicon deposition processes are developed and optimized in smaller R&D KA... more In the first step, silicon deposition processes are developed and optimized in smaller R&D KAI™-M systems. Combined with our high quality in-house developed LPCVD (Low Pressure Chemical Vapor Deposition) ZnO stabilized record cell efficiencies of 10.09% have been realized for a single-junction amorphous silicon solar cell device and of 11.91% for a Micromorph (amorphous/microcrystalline silicon) tandem cell. Both stabilized efficiencies have been independently confirmed by NREL (Golden, USA) and represent record champion cells. In the next phase these process parameters are transferred to industrial size PECVD reactors of 1.4 m2 (KAI™-1200) area. We achieved in R&D for 1.4 m2 amorphous silicon p-i-n single-junction modules initial output powers of 139.1 W respectively 163 W for Micromorph tandems. The Micromorph module has been indoor light-soaked and resulted in a stabilized output power of remarkable 143 W corresponding to an overall stabilized module efficiency of 10.0%. For the a-Si:H p-i-n module we expect a module output power of 115.2 W after light-soaking based on our stability experience on small area modules. Both large area modules were manufactured using our in-house developed LPCVD TCO. At present Oerlikon customers produced in total more than 4.5 Mio modules (a-Si single-junction or Micromorph tandems) which all together correspond to a cumulated total power of at least 450 MWp. Recently Oerlikon Solar introduced its new improved production fab concept, the so-called ThinFab™, which brings total module production costs down to remarkable 0.5 €/Wp at a 120 MWp output capacity.
Energy Procedia, 2012
Developments in small R&D KAI TM systems have resulted in NREL-confirmed stabilised cell efficien... more Developments in small R&D KAI TM systems have resulted in NREL-confirmed stabilised cell efficiencies of 10.09 % for amorphous p-in and 11.91% for Micromorph tandem devices. Up-scaling of the processes to 1.4 m 2 R&D equipment has so far lead to modules having initial powers of 139.1 W for amorphous silicon and 163 W for Micromorph tandem respectively. At present Oerlikon customers produced in total more than 4.5 million modules (a-Si:H p-in or Micromorph tandem) which all together correspond to a cumulative total power of over 450 MW p. Recently Oerlikon Solar introduced its new improved production concept, the so-called ThinFab TM , which brings module production costs down to remarkable 0.5 €/W p at a capacity of 120 MW p .
MRS Proceedings, 2010
Amorphous silicon single-junction p-i-n and Micromorph tandem solar cells are deposited in KAI-M ... more Amorphous silicon single-junction p-i-n and Micromorph tandem solar cells are deposited in KAI-M reactors on in-house developed LPCVD ZnO front TCO's. An a-Si:H p-i-n cell with a stabilized efficiency of 10.09 % on 1 cm2 has been independently confirmed by NREL. An alternative ZnO/a-Si:H cell process with an intrinsic absorber of only 180 nm has reached 10.06 % NREL confirmed stabilized efficiencies as well. Up-scaling of such thin cells to 10x10 cm2 mini-modules has led to an aperture module efficiency of stabilized 9.20 ± 0.19 % as well independently confirmed by ESTI of JRC Ispra.Micromorph tandem cells with stabilized efficiencies of 11.0% have been achieved on as-grown LPCVD ZnO front TCO at bottom cell thickness of just 1.3 μm in combination with the in-house developed AR concept. Applying an advanced LPCVD ZnO front TCO stabilized tandem cells of 10.6 % have been realized at a bottom cell thickness of only 0.8 μm. Implementing in-situ intermediate reflectors in Micromorph...
Energy Procedia, 2010
In this study recent results of Micromorph thin film silicon tandem cells with n-doped silicon ox... more In this study recent results of Micromorph thin film silicon tandem cells with n-doped silicon oxide based intermediate reflectors deposited in the KAI-M industrial PECVD reactor are discussed. From the optical analysis of the devices, specific features in the reflection spectrum attributed to the incorporated intermediate reflector can be observed. In particular, the influence of the Transparent Conductive Oxide (TCO) layer roughness on the reflection spectrum of the cells is studied. Compared to commercial SnO 2, reflection losses are reduced and photocurrents are increased by using rougher front TCO-layers like LPCVD-ZnO which should lead to potentially higher efficiencies at same silicon absorber thicknesses. Micromorph tandem cells with intermediate reflector on ZnO leads to 10.18 % efficiency after 1000 h of light-soaking, whereas 10.35 % have been achieved on commercial SnO 2 .
Sensors and Actuators A: Physical, 2006
This paper reports on a process flow and characterization for the growth of released carbon nanot... more This paper reports on a process flow and characterization for the growth of released carbon nanotubes on polysilicon microelectromechanical devices. We describe a series of post-processing steps to achieve successful integration of CNTs directly into a triple layer polysilicon surface micromachined chip. Individual or multiple tubes can be directly grown between movable posts and electrically connected. The process is characterized to the point where minimum feature sizes and minimum spacing of catalytic seeds are determined as a function of the catalytic solution concentration. We show scanning electron microscopy images and Raman spectroscopy recordings that validate the direct growth of nanotubes. By integrating nanotube growth into batch fabricated microsystems, direct and reliable measurement techniques can be developed and used to accelerate research and identification of nanotube transducer properties. The reported technology is opening the way to the synthesis and evaluation of mechanical nano-scale transducers based on carbon nanotubes.
IEEE Transactions on Education, 2009
A microelectro-mechanical systems (MEMS) laboratory course (MEMSlab) in the Mechanical and Proces... more A microelectro-mechanical systems (MEMS) laboratory course (MEMSlab) in the Mechanical and Process Engineering Department at the Swiss Federal Institute of Technology (ETH Zurich), is presented. The course has been taught for four years and has been attended primarily by Master's students from mechanical and electrical engineering; since fall 2006, the course has been required within the Master of Micro and Nanosystems curriculum. Students participating in the MEMSlab course learn the operational principles of comb-structure accelerometers, as well as how to fabricate, package, and test single-axis accelerometers, thereby being exposed to the multiple disciplines and practical topics that are involved in the production of MEMS and microelectronics. Based upon the course assessments, which are summarized and discussed, one of the benefits of MEMSlab is the course format. This format, which includes a dedicated course text, referred to as the "script," and two introductory lecture sessions, has allowed students without prior semiconductor physics or process experience to participate fully in the course and to learn the major elements of MEMS fabrication. The MEMSlab course provides students at the ETH Zurich with their sole opportunity to experience clean room microfabrication through a structured course setting, since there are no other solid-state device fabrication laboratory courses offered at the ETH Zurich.
![Research paper thumbnail of Characterisation of LPE thin film silicon on low cost silicon substrates [solar cells]](https://attachments.academia-assets.com/109399777/thumbnails/1.jpg)
](Conference Record of the Twenty-Eighth IEEE Photovoltaic Specialists Conference - 2000 (Cat. No.00CH37036)
Thin Si layers of 8-30 µm were grown by LPE on upgraded metallurgical (UMG) multicrystalline Si s... more Thin Si layers of 8-30 µm were grown by LPE on upgraded metallurgical (UMG) multicrystalline Si substrates. A melt back step just before the growth process circumvented the additional supply of Si to the melt. Solar cells, realized by using a simple screenprinting process, reached efficiencies up to η = 6% (FF = 74.1%, JSC = 14.7 mA/cm², VOC = 551 mV) without antireflection coating. The influence of impurity diffusion from the substrate into the active layer and the impurity incorporation from the In solution during the growth process have been studied (e.g. by SIMS). Using Secco etching, LBIC and spectral response measurements it could be shown that the local Isc is not limited by impurities and further increases in Isc could be achieved by growing thicker epilayers. The results of the investigations underline the good crystal quality of the epilayers on UMG Si substrates and enables the further increase of the efficiency.
L'invention concerne un procede pour fabriquer une cellule solaire p-i-n solaire a base de si... more L'invention concerne un procede pour fabriquer une cellule solaire p-i-n solaire a base de silicium amorphe. La cellule comprend un revetement antireflechissant et des contacts avant et arriere ZnO dope par LPCVD, lesdits contacts avant et arriere ZnO dope par LPCVD etant des films polycrystallins constitues de gros grains dont les extremites apparaissent au niveau de la surface de croissance sous forme de pyramides. Le procede consiste : a deposer ledit contact avant par un procede de depot chimique en phase vapeur sous pression reduite (LPCVD); a deposer les couches de silicium sur ladite cellule p-i-n solaire par depot chimique en phase vapeur active par plasma; a deposer ledit contact arriere par LPCVD; et a disposer le revetement antireflechissant. La cellule p-i-n solaire a base de silicium amorphe peut atteindre une efficacite stabilisee de 10,09 %.
... Click to zoom in 2 pages available to preview. Available from www.eupvsec-proceedings.com. ..... more ... Click to zoom in 2 pages available to preview. Available from www.eupvsec-proceedings.com. ... as front TCO The ZnO layers presented in this work (namely type-A and type-B) were modified compared to the layers used in a previous work presented at the 23rd EU PVSEC [7]. In ...
L'invention concerne un procede de fabrication d'une cellule tandem micromorphe. La cellu... more L'invention concerne un procede de fabrication d'une cellule tandem micromorphe. La cellule tandem micromorphe comprend une cellule de base μc-Si:H et une cellule superieure a-Si:H, une couche avant de contact LPCVD en ZnO et une couche arriere de contact en ZnO en combinaison avec un reflecteur blanc. Le procede comprend les etapes qui consistent a appliquer un concept AR - Anti-Reflechissant - sur la cellule tandem micromorphe et a implementer un reflecteur intermediaire dans la cellule tandem micromorphe. La cellule tandem micromorphe permet d'obtenir un rendement stabilise de 10,6 %.
Solar Energy Materials and Solar Cells, 2016
The influence of working pressure and inter-electrode gap distance on the quality of microcrystal... more The influence of working pressure and inter-electrode gap distance on the quality of microcrystalline silicon prepared by PECVD at 40 MHz in three different KAI™ reactors designs with inter-electrode gaps of 28 mm, 16 mm and 7 mm has been investigated. The microcrystalline devices were implemented and studied as bottom cells in MICROMORPH™ tandem modules or processed with an optical filter to simulate the absorption of a top cell on a module size of 1.43 m 2. Increasing the working pressure from 250 Pa to 2000 Pa resulted in an improvement of the efficiency of 1% absolute due to improvement in the open circuit voltage V oc and the fill factor FF. The influence of the deposition rate on the quality of the intrinsic absorber layers has been investigated and optimized. An unconventional crystallinity profile throughout the intrinsic absorber layer has been developed to further improve either the current density J sc or V oc and FF. By controlling and tuning the Raman crystallinity a very high open circuit voltage V oc of 41.42 V in a tandem cell design in full size modules (1.43 m 2) could be realized.
The 13th International Conference on Solid-State Sensors, Actuators and Microsystems, 2005. Digest of Technical Papers. TRANSDUCERS '05.
We present a process flow and characterization for the growth of freestanding carbon nanotubes on... more We present a process flow and characterization for the growth of freestanding carbon nanotubes on a polysihcon microelectromechanical device. Individual or multiple tubes can be directly grown bctween movable posts and electrically connected. The process is characterized to the point where minimum feature sizes of catalytic islands are determined as a function of the catalytic solution concentration. We show scanning electron microscopy pictures that validate the direct growth of nanotubes. The reported technology is batch-fabrication compatible as opposed to discrete fabrication processes and is opening the way to the synthesis and evaluation of mechanical nano-scale transduccrs based on carbon nanotubes. microscope (AFM) to apply a force on a suspended CNT while measuring the electric conductivity [6,7]. We suggest the usage of microsystem technology as a flexible platform for system design to mechanically deform and electrically sense CNTs in various ways (axial & torsional strain, bending, resonance) [8], given that the CNTs can be accurately integrated. Schematically shown in Fig. 1 is a proposed MEMS based test stand. bridgedCNT
Solar Energy Materials and Solar Cells, 2015
Light management is fundamental for achieving high performance thin-film silicon solar cells. We ... more Light management is fundamental for achieving high performance thin-film silicon solar cells. We highlight important developments of light management for record modules subdivided into several main categories: (a) reduction of reflection at interfaces by introducing antireflective layers; (b) reduction of parasitic losses in transparent conductive oxide layers; (c) improvement of light scattering combined with transparent conductive oxide surface morphology optimization; and (d) balancing of top cell and bottom cell currents by reflective layers. Specific aspects related to industrial production of large area modules are discussed including transparency/conductivity trade-offs, optimized deposition rates and coating uniformities.
In September 2010 the PEPPER project started after receiving a grant under the Framework Programm... more In September 2010 the PEPPER project started after receiving a grant under the Framework Programme FP7 for research of the European Union, coordinated by the DG Energy of the European Commission (no. 249782). The PEPPER project tackles major factors relating to micromorph module efficiency and production cost by assessing the influences of glass, TCO and silicon deposition (including in-situ cleaning). The project bridges the gap between research and industrial application by executing new developments and improvements in the field of TCO and PECVD reactors and processes and transferring them to production plants where the full impact on module efficiency and costs can be evaluated. The joint goal of this project is the demonstration of a 157Wp (stable) micromorph module with a cost of ownership (CoO) of 0.5€/Wp. Succeeding in this project will ensure the competitiveness of the Micromorph technology and further approach the final goal of grid parity. The first results of the project...
Diese Arbeit leistet einen Beitrag zur Kostenreduzierung bei der Herstellung von Si-Solarzellen d... more Diese Arbeit leistet einen Beitrag zur Kostenreduzierung bei der Herstellung von Si-Solarzellen durch die Anwendung einer speziellen LPE-Technologie auf UMG Si-Substraten. Dadurch wurde der Einsatz von EG-Si bei der LPE-Solarzellenherstellung erstmals völlig überflüssig. Eine neue, industriell kompatible Siebdrucktechnologie ermöglichte die Realisierung von kostengünstigen und effizienten Solarzellen.Hochwertige Si-Schichten wurden mit einer horizontalen LPE-Anlage auf unterschiedlichen Si-Substraten abgeschieden. Die Verwendung von UMG-Si als Substrat gelang, da die Diffusion von Verunreinigungen aus dem Substrat in die LPE-Schicht unterhalb der SIMS-Nachweisgrenze lag. Mit Hall-Messungen wurden LPE-Schichten mit unterschiedlichen Herstellungsparametern charakterisiert und optimiert. Durch chemisches Ätzen gelang die optische Auflösung von LPE-Schicht, UMG-Substrat und deren Übergang. Aus der LBIC-Analyse und PC1D-Simulation wurde die optimale LPE-Schichtdicke berechnet.Die Abschei...
A stabilized record efficiency of 9.1 % for an a-Si:H p-i-n test cell (1 cm2) could be obtained t... more A stabilized record efficiency of 9.1 % for an a-Si:H p-i-n test cell (1 cm2) could be obtained thanks to the enhanced light-trapping properties of LPCVD ZnO as front TCO and a rigorous process optimisation. ESTI of JRC independently confirms a stabilized aperture efficiency of 8.32 % for a mini-module based on a-Si:H p-i-n with ZnO as front TCO. 1.4 m2 large-area amorphous silicon p-i-n modules with 123 W initial power have been fabricated implementing such ZnO layers as front TCO. Micromorph test cells with initial efficiencies of 12.1 % have been prepared in the KAI-M reactor. Up-scaling of Micromorph tandems to mini-modules and 1.4 m2 area modules have led to remarkable high efficiencies. First results applying in-situ deposited intermediate reflector layers in the KAI-M PECVD system reveal promising results for next generation of Micromorph tandem devices.
2011 37th IEEE Photovoltaic Specialists Conference, 2011
ABSTRACT This work reports on the optimization of amorphous-microcrystalline silicon tandem solar... more ABSTRACT This work reports on the optimization of amorphous-microcrystalline silicon tandem solar cells and modules on LPCVD ZnO on 1.4m2 substrate size. The focus is on the optimization of PECVD deposition of n-and p-type doped layers for the microcrystalline silicon bottom cell deposited in a commercially available Oerlikon Solar KAI PECVD system. For this type of layers, both electro-optical properties with respect to cell and module efficiency as well as deposition rate with respect to throughput are of interest. A novel silicon oxide based n-layer which enhances current density of the solar cell by reducing absorption loss was introduced in the bottom cell design. An appropriate optimization of the n-layer was found crucial to achieve a suitable device performance. In a second step, the increase of the deposition rate of the n-and p-layers was addressed to match the throughput requirements for an industrial low cost production process.
Conference Record of the IEEE Photovoltaic Specialists Conference, 2011
In the first step, silicon deposition processes are developed and optimized in smaller R&D KA... more In the first step, silicon deposition processes are developed and optimized in smaller R&D KAI™-M systems. Combined with our high quality in-house developed LPCVD (Low Pressure Chemical Vapor Deposition) ZnO stabilized record cell efficiencies of 10.09% have been realized for a single-junction amorphous silicon solar cell device and of 11.91% for a Micromorph (amorphous/microcrystalline silicon) tandem cell. Both stabilized efficiencies have been independently confirmed by NREL (Golden, USA) and represent record champion cells. In the next phase these process parameters are transferred to industrial size PECVD reactors of 1.4 m2 (KAI™-1200) area. We achieved in R&D for 1.4 m2 amorphous silicon p-i-n single-junction modules initial output powers of 139.1 W respectively 163 W for Micromorph tandems. The Micromorph module has been indoor light-soaked and resulted in a stabilized output power of remarkable 143 W corresponding to an overall stabilized module efficiency of 10.0%. For the a-Si:H p-i-n module we expect a module output power of 115.2 W after light-soaking based on our stability experience on small area modules. Both large area modules were manufactured using our in-house developed LPCVD TCO. At present Oerlikon customers produced in total more than 4.5 Mio modules (a-Si single-junction or Micromorph tandems) which all together correspond to a cumulated total power of at least 450 MWp. Recently Oerlikon Solar introduced its new improved production fab concept, the so-called ThinFab™, which brings total module production costs down to remarkable 0.5 €/Wp at a 120 MWp output capacity.
Energy Procedia, 2012
Developments in small R&D KAI TM systems have resulted in NREL-confirmed stabilised cell efficien... more Developments in small R&D KAI TM systems have resulted in NREL-confirmed stabilised cell efficiencies of 10.09 % for amorphous p-in and 11.91% for Micromorph tandem devices. Up-scaling of the processes to 1.4 m 2 R&D equipment has so far lead to modules having initial powers of 139.1 W for amorphous silicon and 163 W for Micromorph tandem respectively. At present Oerlikon customers produced in total more than 4.5 million modules (a-Si:H p-in or Micromorph tandem) which all together correspond to a cumulative total power of over 450 MW p. Recently Oerlikon Solar introduced its new improved production concept, the so-called ThinFab TM , which brings module production costs down to remarkable 0.5 €/W p at a capacity of 120 MW p .
MRS Proceedings, 2010
Amorphous silicon single-junction p-i-n and Micromorph tandem solar cells are deposited in KAI-M ... more Amorphous silicon single-junction p-i-n and Micromorph tandem solar cells are deposited in KAI-M reactors on in-house developed LPCVD ZnO front TCO's. An a-Si:H p-i-n cell with a stabilized efficiency of 10.09 % on 1 cm2 has been independently confirmed by NREL. An alternative ZnO/a-Si:H cell process with an intrinsic absorber of only 180 nm has reached 10.06 % NREL confirmed stabilized efficiencies as well. Up-scaling of such thin cells to 10x10 cm2 mini-modules has led to an aperture module efficiency of stabilized 9.20 ± 0.19 % as well independently confirmed by ESTI of JRC Ispra.Micromorph tandem cells with stabilized efficiencies of 11.0% have been achieved on as-grown LPCVD ZnO front TCO at bottom cell thickness of just 1.3 μm in combination with the in-house developed AR concept. Applying an advanced LPCVD ZnO front TCO stabilized tandem cells of 10.6 % have been realized at a bottom cell thickness of only 0.8 μm. Implementing in-situ intermediate reflectors in Micromorph...
Energy Procedia, 2010
In this study recent results of Micromorph thin film silicon tandem cells with n-doped silicon ox... more In this study recent results of Micromorph thin film silicon tandem cells with n-doped silicon oxide based intermediate reflectors deposited in the KAI-M industrial PECVD reactor are discussed. From the optical analysis of the devices, specific features in the reflection spectrum attributed to the incorporated intermediate reflector can be observed. In particular, the influence of the Transparent Conductive Oxide (TCO) layer roughness on the reflection spectrum of the cells is studied. Compared to commercial SnO 2, reflection losses are reduced and photocurrents are increased by using rougher front TCO-layers like LPCVD-ZnO which should lead to potentially higher efficiencies at same silicon absorber thicknesses. Micromorph tandem cells with intermediate reflector on ZnO leads to 10.18 % efficiency after 1000 h of light-soaking, whereas 10.35 % have been achieved on commercial SnO 2 .
Sensors and Actuators A: Physical, 2006
This paper reports on a process flow and characterization for the growth of released carbon nanot... more This paper reports on a process flow and characterization for the growth of released carbon nanotubes on polysilicon microelectromechanical devices. We describe a series of post-processing steps to achieve successful integration of CNTs directly into a triple layer polysilicon surface micromachined chip. Individual or multiple tubes can be directly grown between movable posts and electrically connected. The process is characterized to the point where minimum feature sizes and minimum spacing of catalytic seeds are determined as a function of the catalytic solution concentration. We show scanning electron microscopy images and Raman spectroscopy recordings that validate the direct growth of nanotubes. By integrating nanotube growth into batch fabricated microsystems, direct and reliable measurement techniques can be developed and used to accelerate research and identification of nanotube transducer properties. The reported technology is opening the way to the synthesis and evaluation of mechanical nano-scale transducers based on carbon nanotubes.
IEEE Transactions on Education, 2009
A microelectro-mechanical systems (MEMS) laboratory course (MEMSlab) in the Mechanical and Proces... more A microelectro-mechanical systems (MEMS) laboratory course (MEMSlab) in the Mechanical and Process Engineering Department at the Swiss Federal Institute of Technology (ETH Zurich), is presented. The course has been taught for four years and has been attended primarily by Master's students from mechanical and electrical engineering; since fall 2006, the course has been required within the Master of Micro and Nanosystems curriculum. Students participating in the MEMSlab course learn the operational principles of comb-structure accelerometers, as well as how to fabricate, package, and test single-axis accelerometers, thereby being exposed to the multiple disciplines and practical topics that are involved in the production of MEMS and microelectronics. Based upon the course assessments, which are summarized and discussed, one of the benefits of MEMSlab is the course format. This format, which includes a dedicated course text, referred to as the "script," and two introductory lecture sessions, has allowed students without prior semiconductor physics or process experience to participate fully in the course and to learn the major elements of MEMS fabrication. The MEMSlab course provides students at the ETH Zurich with their sole opportunity to experience clean room microfabrication through a structured course setting, since there are no other solid-state device fabrication laboratory courses offered at the ETH Zurich.
Conference Record of the Twenty-Eighth IEEE Photovoltaic Specialists Conference - 2000 (Cat. No.00CH37036)
Thin Si layers of 8-30 µm were grown by LPE on upgraded metallurgical (UMG) multicrystalline Si s... more Thin Si layers of 8-30 µm were grown by LPE on upgraded metallurgical (UMG) multicrystalline Si substrates. A melt back step just before the growth process circumvented the additional supply of Si to the melt. Solar cells, realized by using a simple screenprinting process, reached efficiencies up to η = 6% (FF = 74.1%, JSC = 14.7 mA/cm², VOC = 551 mV) without antireflection coating. The influence of impurity diffusion from the substrate into the active layer and the impurity incorporation from the In solution during the growth process have been studied (e.g. by SIMS). Using Secco etching, LBIC and spectral response measurements it could be shown that the local Isc is not limited by impurities and further increases in Isc could be achieved by growing thicker epilayers. The results of the investigations underline the good crystal quality of the epilayers on UMG Si substrates and enables the further increase of the efficiency.