Alvin Compaan - Academia.edu (original) (raw)
Papers by Alvin Compaan
A method of making a diode structure includes the step of depositing a transparent electrode laye... more A method of making a diode structure includes the step of depositing a transparent electrode layer of any one or more of the group ZnO, ZnS and CdO onto a substrate layer, and depositing an active semiconductor junction having an n-type layer and a p-type layer onto the transparent electrode layer under process conditions that avoid substantial degradation of the electrode layer. A back electrode coating layer is applied to form a diode structure
Bookmarks Related papers MentionsView impact
Conference Record of the Thirty-first IEEE Photovoltaic Specialists Conference, 2005.
We have used the MR-CAT beamline of the Advanced Photon Source at Argonne National Laboratory to ... more We have used the MR-CAT beamline of the Advanced Photon Source at Argonne National Laboratory to study the fine structure in the Cu K-edge X-ray absorption in 2 μm thick polycrystalline films of CdTe on fused silica. 4 nm of evaporated Cu is diffused either with or without prior vapor CdCl2 treatments in dry air. The phase-uncorrected radial distribution function inferred from the absorption fine structure indicates predominantly Cu2Te when Cu is diffused into the as-deposited CdTe film but indicates a Cu2O environment when Cu is diffused after the vapor CdCl2 treatment. We believe most of the diffused Cu decorates grain boundaries as oxides, consistent with the low doping densities typically observed in CdTe solar cells. This Cu2O likely plays a role in grain-boundary passivation. We also found that the chemical environment around Cu atoms in both CdTe and real cells can change with light soaking. This instability of Cu2O in sputtered CdTe could contribute to cell degradation.
Bookmarks Related papers MentionsView impact
Conference Record of the Thirty-first IEEE Photovoltaic Specialists Conference, 2005.
Large scale (gigawatts/yr) manufacturing of CdTe PV modules may be constrained due to the limited... more Large scale (gigawatts/yr) manufacturing of CdTe PV modules may be constrained due to the limited availability of the relatively rare (Te) element and the volume of potentially hazardous (Cd) material being used in 3-8 μm thick CdTe absorber layer. This work is focused on cells with much thinner CdTe layers. Magnetron sputtering was used to prepare a series of CdS/CdTe
Bookmarks Related papers MentionsView impact
ECS Transactions, 2015
ALD NiO was deposited on silicon and glass substrates by applying alternative pulses of Ni(amd) (... more ALD NiO was deposited on silicon and glass substrates by applying alternative pulses of Ni(amd) (AccuDEPTM Ni, Dow Chemical), and water. The film deposition rate at 200°C was 0.25-0.45 Å/cycle. The material properties of the NiO films were characterized using FESEM, AFM, UV-Vis-NIR spectrometer, and GIXRD. The optimized thin ALD NiO film was applied to very thin (500nm) CdTe cells in order to evaluate the potential of the ALD NiO film as a HT-EBL layer. The ALD NiO integrated CdTe cells enhanced Voc and FF, and offered 15% improvement in PCE compared with the control cells.
Bookmarks Related papers MentionsView impact
Bookmarks Related papers MentionsView impact
Bookmarks Related papers MentionsView impact
Bookmarks Related papers MentionsView impact
Cadmium telluride (CdTe) solar cells have become very successful for large scale application of p... more Cadmium telluride (CdTe) solar cells have become very successful for large scale application of photovoltaic energy conversion with Ohio-based solar cell manufacturer, First Solar, now the largest manufacturer of thin-film cells in the world. Although CdTe solar cells have shown laboratory efficiencies in excess of 16.5% its realistic potential efficiency is well above 20%. High-resistivity transparent oxide buffer layers (HRT's) added between the transparent conducting oxide (TCO) and CdS layers in CdTe solar cells can enhance the performance of the device. Our results show an increase in efficiency with the HRT layer with the greatest contribution coming from improved fill factor (FF). Open circuit-voltage (Voc) and short-circuit current (Jsc) stay relatively constant. The effect of different materials as the HRT layer on the cell structure TCO/HRT/CdS/CdTe/Cu/Au was investigated using commercially available SnO2:F as the TCO. The study included ZnO, ZnO:Al, SiO2, SnO2 and Al2...
Bookmarks Related papers MentionsView impact
Conference Record of the Twenty-Ninth IEEE Photovoltaic Specialists Conference, 2002.
... The synchmtron studies were partly supported by MRGAT and the Advanced Photon Source. The sum... more ... The synchmtron studies were partly supported by MRGAT and the Advanced Photon Source. The summer research experience for undergraduate Katie Hinko was partially supported by NSF. ' Present address: Morehead State Univ. Morehead. ... I7l PY Yu. and M. Cardona. ...
Bookmarks Related papers MentionsView impact
Conference Record of the Thirty-first IEEE Photovoltaic Specialists Conference, 2005.
We describe the application of sputter deposition processes to the fabrication of CdS/CdTe solar ... more We describe the application of sputter deposition processes to the fabrication of CdS/CdTe solar cells on light weight, flexible substrates in both the substrate and superstrate configurations. We have fabricated CdS/CdTe cells on molybdenum foil and Kapton polyimide. The Mo-based devices are among the best reported for substrate configuration CdTe solar cells, with efficiencies of ∼7% at AM1.5.
Bookmarks Related papers MentionsView impact
MRS Proceedings, 2001
ABSTRACTHigh efficiency CdTe solar cells are typically grown with CdTe thicknesses from 3 to 15 μ... more ABSTRACTHigh efficiency CdTe solar cells are typically grown with CdTe thicknesses from 3 to 15 μm, although the thickness required for 90% absorption of the incident irradiation at 800 nm is only ∼1 μm. In this paper, we present the effect of CdTe thickness reduction on the performance of CdS/CdTe solar cells in which both the CdS and CdTe films were grown by sputtering. We produced a series of cells with different CdTe thickness (from 0.5 to 3.0 μm), and held the CdS thickness and back-contact-processing constant. The effect of CdTe thickness reduction on the diffusion of CdS into CdTe was studied using optical absorption and x-ray diffraction techniques. Only slight decreases occur in open-circuit voltage, short-circuit current, and fill factor with decrease in CdTe film thickness to 1.0 μm. Almost 10% efficient cells were obtained with 1 μm CdTe. Below 1 μm, all cell parameters decrease more rapidly, including the red quantum efficiency.
Bookmarks Related papers MentionsView impact
2008 33rd IEEE Photovolatic Specialists Conference, 2008
We have used the MR-CAT beam-line of the Ad vanced Photon Source (APS) at Argonne National Labora... more We have used the MR-CAT beam-line of the Ad vanced Photon Source (APS) at Argonne National Labora tory to study Cu x-ray fluorescence (XRF) in CdS/CdTe IAu structures on fused silica without transparent conduc tive oxide (TCO). After a "peel-off' process that separates the ...
Bookmarks Related papers MentionsView impact
Bookmarks Related papers MentionsView impact
Journal of Applied Physics, 2014
Bookmarks Related papers MentionsView impact
2010 35th IEEE Photovoltaic Specialists Conference, 2010
ABSTRACT Photoluminescence (PL) in CdTe in the range from 0.7 eV to 1.5 eV provides a great deal ... more ABSTRACT Photoluminescence (PL) in CdTe in the range from 0.7 eV to 1.5 eV provides a great deal of information about shallow and deep defects and the role of CdCl2 activation treatments in changing the density of these defects. We have used an InGaAs diode-array detector to study this region at 10 K in as-sputtered films and CdCl2-treated films. In the region from 0.7 to 1.2 eV we find a series of peaks from deep donor-acceptor pairs that is quite sensitive to the sputter deposition conditions in the range of pressures from 2.5 mTorr to 30 mTorr. In the near-band-edge region from 1.3 to 1.5 eV, studied from the contact side of cells, we find PL peak shifts indicative of some S alloying at the back surface as the chloride activation time increases.
Bookmarks Related papers MentionsView impact
2009 34th IEEE Photovoltaic Specialists Conference (PVSC), 2009
ABSTRACT Fabricating high-efficiency CdS/CdTe solar cells with ultra-thin (below 1 μm) absorber l... more ABSTRACT Fabricating high-efficiency CdS/CdTe solar cells with ultra-thin (below 1 μm) absorber layers is a challenging yet highly desirable step in improving CdTe technology. Typically solar cell performance decreases due to shunting, incomplete absorption (deep penetration loss), fully depleted CdTe layers or interference between the main and the back contact junction when the CdTe layer thickness approaches a certain limit. While some of these losses are fundamental, others can be minimized by careful optimization of the fabrication steps. We present the results of such optimization.
Bookmarks Related papers MentionsView impact
Photovoltaic (PV) cell structures having an integral light scattering interface layer configured ... more Photovoltaic (PV) cell structures having an integral light scattering interface layer configured to diffuse or scatter light prior to entering a semiconductor material and methods of making the same are described
Bookmarks Related papers MentionsView impact
Bookmarks Related papers MentionsView impact
Conference Record of the Twenty-Ninth IEEE Photovoltaic Specialists Conference, 2002.
Reactively sputtered ZnTe:N is a close valence-band match to CdTe, transparent below 2.2 eV and t... more Reactively sputtered ZnTe:N is a close valence-band match to CdTe, transparent below 2.2 eV and therefore an attractive candidate for a back contact/tunnel junction in tandem cells using CdTe or CdZnTe top cells. We report on measurements of the optical emission spectra of N2 during reactive sputtering as part of the doping optimization. For materials characterization, a series of films
Bookmarks Related papers MentionsView impact
Nano letters, Jan 13, 2013
We have discovered that films of carbon single wall nanotubes (SWNTs) make excellent back contact... more We have discovered that films of carbon single wall nanotubes (SWNTs) make excellent back contacts to CdTe devices without any modification to the CdTe surface. Efficiencies of SWNT-contacted devices are slightly higher than otherwise identical devices formed with standard Au/Cu back contacts. The SWNT layer is thermally stable and easily applied with a spray process, and SWNT-contacted devices show no signs of degradation during accelerated life testing.
Bookmarks Related papers MentionsView impact
A method of making a diode structure includes the step of depositing a transparent electrode laye... more A method of making a diode structure includes the step of depositing a transparent electrode layer of any one or more of the group ZnO, ZnS and CdO onto a substrate layer, and depositing an active semiconductor junction having an n-type layer and a p-type layer onto the transparent electrode layer under process conditions that avoid substantial degradation of the electrode layer. A back electrode coating layer is applied to form a diode structure
Bookmarks Related papers MentionsView impact
Conference Record of the Thirty-first IEEE Photovoltaic Specialists Conference, 2005.
We have used the MR-CAT beamline of the Advanced Photon Source at Argonne National Laboratory to ... more We have used the MR-CAT beamline of the Advanced Photon Source at Argonne National Laboratory to study the fine structure in the Cu K-edge X-ray absorption in 2 μm thick polycrystalline films of CdTe on fused silica. 4 nm of evaporated Cu is diffused either with or without prior vapor CdCl2 treatments in dry air. The phase-uncorrected radial distribution function inferred from the absorption fine structure indicates predominantly Cu2Te when Cu is diffused into the as-deposited CdTe film but indicates a Cu2O environment when Cu is diffused after the vapor CdCl2 treatment. We believe most of the diffused Cu decorates grain boundaries as oxides, consistent with the low doping densities typically observed in CdTe solar cells. This Cu2O likely plays a role in grain-boundary passivation. We also found that the chemical environment around Cu atoms in both CdTe and real cells can change with light soaking. This instability of Cu2O in sputtered CdTe could contribute to cell degradation.
Bookmarks Related papers MentionsView impact
Conference Record of the Thirty-first IEEE Photovoltaic Specialists Conference, 2005.
Large scale (gigawatts/yr) manufacturing of CdTe PV modules may be constrained due to the limited... more Large scale (gigawatts/yr) manufacturing of CdTe PV modules may be constrained due to the limited availability of the relatively rare (Te) element and the volume of potentially hazardous (Cd) material being used in 3-8 μm thick CdTe absorber layer. This work is focused on cells with much thinner CdTe layers. Magnetron sputtering was used to prepare a series of CdS/CdTe
Bookmarks Related papers MentionsView impact
ECS Transactions, 2015
ALD NiO was deposited on silicon and glass substrates by applying alternative pulses of Ni(amd) (... more ALD NiO was deposited on silicon and glass substrates by applying alternative pulses of Ni(amd) (AccuDEPTM Ni, Dow Chemical), and water. The film deposition rate at 200°C was 0.25-0.45 Å/cycle. The material properties of the NiO films were characterized using FESEM, AFM, UV-Vis-NIR spectrometer, and GIXRD. The optimized thin ALD NiO film was applied to very thin (500nm) CdTe cells in order to evaluate the potential of the ALD NiO film as a HT-EBL layer. The ALD NiO integrated CdTe cells enhanced Voc and FF, and offered 15% improvement in PCE compared with the control cells.
Bookmarks Related papers MentionsView impact
Bookmarks Related papers MentionsView impact
Bookmarks Related papers MentionsView impact
Bookmarks Related papers MentionsView impact
Cadmium telluride (CdTe) solar cells have become very successful for large scale application of p... more Cadmium telluride (CdTe) solar cells have become very successful for large scale application of photovoltaic energy conversion with Ohio-based solar cell manufacturer, First Solar, now the largest manufacturer of thin-film cells in the world. Although CdTe solar cells have shown laboratory efficiencies in excess of 16.5% its realistic potential efficiency is well above 20%. High-resistivity transparent oxide buffer layers (HRT's) added between the transparent conducting oxide (TCO) and CdS layers in CdTe solar cells can enhance the performance of the device. Our results show an increase in efficiency with the HRT layer with the greatest contribution coming from improved fill factor (FF). Open circuit-voltage (Voc) and short-circuit current (Jsc) stay relatively constant. The effect of different materials as the HRT layer on the cell structure TCO/HRT/CdS/CdTe/Cu/Au was investigated using commercially available SnO2:F as the TCO. The study included ZnO, ZnO:Al, SiO2, SnO2 and Al2...
Bookmarks Related papers MentionsView impact
Conference Record of the Twenty-Ninth IEEE Photovoltaic Specialists Conference, 2002.
... The synchmtron studies were partly supported by MRGAT and the Advanced Photon Source. The sum... more ... The synchmtron studies were partly supported by MRGAT and the Advanced Photon Source. The summer research experience for undergraduate Katie Hinko was partially supported by NSF. ' Present address: Morehead State Univ. Morehead. ... I7l PY Yu. and M. Cardona. ...
Bookmarks Related papers MentionsView impact
Conference Record of the Thirty-first IEEE Photovoltaic Specialists Conference, 2005.
We describe the application of sputter deposition processes to the fabrication of CdS/CdTe solar ... more We describe the application of sputter deposition processes to the fabrication of CdS/CdTe solar cells on light weight, flexible substrates in both the substrate and superstrate configurations. We have fabricated CdS/CdTe cells on molybdenum foil and Kapton polyimide. The Mo-based devices are among the best reported for substrate configuration CdTe solar cells, with efficiencies of ∼7% at AM1.5.
Bookmarks Related papers MentionsView impact
MRS Proceedings, 2001
ABSTRACTHigh efficiency CdTe solar cells are typically grown with CdTe thicknesses from 3 to 15 μ... more ABSTRACTHigh efficiency CdTe solar cells are typically grown with CdTe thicknesses from 3 to 15 μm, although the thickness required for 90% absorption of the incident irradiation at 800 nm is only ∼1 μm. In this paper, we present the effect of CdTe thickness reduction on the performance of CdS/CdTe solar cells in which both the CdS and CdTe films were grown by sputtering. We produced a series of cells with different CdTe thickness (from 0.5 to 3.0 μm), and held the CdS thickness and back-contact-processing constant. The effect of CdTe thickness reduction on the diffusion of CdS into CdTe was studied using optical absorption and x-ray diffraction techniques. Only slight decreases occur in open-circuit voltage, short-circuit current, and fill factor with decrease in CdTe film thickness to 1.0 μm. Almost 10% efficient cells were obtained with 1 μm CdTe. Below 1 μm, all cell parameters decrease more rapidly, including the red quantum efficiency.
Bookmarks Related papers MentionsView impact
2008 33rd IEEE Photovolatic Specialists Conference, 2008
We have used the MR-CAT beam-line of the Ad vanced Photon Source (APS) at Argonne National Labora... more We have used the MR-CAT beam-line of the Ad vanced Photon Source (APS) at Argonne National Labora tory to study Cu x-ray fluorescence (XRF) in CdS/CdTe IAu structures on fused silica without transparent conduc tive oxide (TCO). After a "peel-off' process that separates the ...
Bookmarks Related papers MentionsView impact
Bookmarks Related papers MentionsView impact
Journal of Applied Physics, 2014
Bookmarks Related papers MentionsView impact
2010 35th IEEE Photovoltaic Specialists Conference, 2010
ABSTRACT Photoluminescence (PL) in CdTe in the range from 0.7 eV to 1.5 eV provides a great deal ... more ABSTRACT Photoluminescence (PL) in CdTe in the range from 0.7 eV to 1.5 eV provides a great deal of information about shallow and deep defects and the role of CdCl2 activation treatments in changing the density of these defects. We have used an InGaAs diode-array detector to study this region at 10 K in as-sputtered films and CdCl2-treated films. In the region from 0.7 to 1.2 eV we find a series of peaks from deep donor-acceptor pairs that is quite sensitive to the sputter deposition conditions in the range of pressures from 2.5 mTorr to 30 mTorr. In the near-band-edge region from 1.3 to 1.5 eV, studied from the contact side of cells, we find PL peak shifts indicative of some S alloying at the back surface as the chloride activation time increases.
Bookmarks Related papers MentionsView impact
2009 34th IEEE Photovoltaic Specialists Conference (PVSC), 2009
ABSTRACT Fabricating high-efficiency CdS/CdTe solar cells with ultra-thin (below 1 μm) absorber l... more ABSTRACT Fabricating high-efficiency CdS/CdTe solar cells with ultra-thin (below 1 μm) absorber layers is a challenging yet highly desirable step in improving CdTe technology. Typically solar cell performance decreases due to shunting, incomplete absorption (deep penetration loss), fully depleted CdTe layers or interference between the main and the back contact junction when the CdTe layer thickness approaches a certain limit. While some of these losses are fundamental, others can be minimized by careful optimization of the fabrication steps. We present the results of such optimization.
Bookmarks Related papers MentionsView impact
Photovoltaic (PV) cell structures having an integral light scattering interface layer configured ... more Photovoltaic (PV) cell structures having an integral light scattering interface layer configured to diffuse or scatter light prior to entering a semiconductor material and methods of making the same are described
Bookmarks Related papers MentionsView impact
Bookmarks Related papers MentionsView impact
Conference Record of the Twenty-Ninth IEEE Photovoltaic Specialists Conference, 2002.
Reactively sputtered ZnTe:N is a close valence-band match to CdTe, transparent below 2.2 eV and t... more Reactively sputtered ZnTe:N is a close valence-band match to CdTe, transparent below 2.2 eV and therefore an attractive candidate for a back contact/tunnel junction in tandem cells using CdTe or CdZnTe top cells. We report on measurements of the optical emission spectra of N2 during reactive sputtering as part of the doping optimization. For materials characterization, a series of films
Bookmarks Related papers MentionsView impact
Nano letters, Jan 13, 2013
We have discovered that films of carbon single wall nanotubes (SWNTs) make excellent back contact... more We have discovered that films of carbon single wall nanotubes (SWNTs) make excellent back contacts to CdTe devices without any modification to the CdTe surface. Efficiencies of SWNT-contacted devices are slightly higher than otherwise identical devices formed with standard Au/Cu back contacts. The SWNT layer is thermally stable and easily applied with a spray process, and SWNT-contacted devices show no signs of degradation during accelerated life testing.
Bookmarks Related papers MentionsView impact