Jens Eriksson | Linköping University (original) (raw)
Papers by Jens Eriksson
High-temperature iridium-gated field effect transistors based on silicon carbide have been used f... more High-temperature iridium-gated field effect transistors based on silicon carbide have been used for sensitive detection of specific volatile organic compounds (VOCs) in concentrations of health concern, for indoor air quality monitoring and control. Formaldehyde, naphthalene, and benzene were studied as hazardous VOCs at parts per billion (ppb) down to sub-ppb levels. The sensor performance and characteristics were investigated at a constant temperature of 330 °C and at different levels of relative humidity up to 60%, showing good stability and repeatability of the sensor response, and excellent detection limits in the sub-ppb range.
2008 IEEE Sensors, 2008
In this work the effect of ambient influence on the electrical conductivity of ZnO films has been... more In this work the effect of ambient influence on the electrical conductivity of ZnO films has been studied. Nanostructured ZnO films (undoped and Ga, Co, Mn doped) were exposed to oxygen (1 -80 vol. %) at temperature range 300 -500 ºС. A dominant effect of ambient influence via oxygen absorption was observed: the intensity of conductivity decrease was found to be proportional with temperature and tends to saturation with time. After oxygen saturation the reversible effect of oxygen adsorption became dominant and contributed to the films conductivity. Oxygen exposed undoped ZnO films revealed high sensitivity for oxygen content change in the ambience, therefore they have been further processed for gas sensor fabrication.
Materials Science Forum, 2013
Large variations have been observed in the thickness uniformity and carrier concentration of epit... more Large variations have been observed in the thickness uniformity and carrier concentration of epitaxial graphene grown on SiC by sublimation for samples grown under identical conditions and on nominally on-axis hexagonal SiC (0001) substrates. We have previously shown that these issues are both related to the morphology of the graphene-SiC surface after sublimation growth.
Materials Science Forum, 2012
ABSTRACT Epitaxially grown single layer graphene on silicon carbide (SiC) resistive sensors were ... more ABSTRACT Epitaxially grown single layer graphene on silicon carbide (SiC) resistive sensors were characterised for NO2 response at room and elevated temperatures, with an n-p type transition observed with increasing NO2 concentration for all sensors. The concentration of NO2 required to cause this transition varied for different graphene samples and is attributed to varying degrees of substrate induced Fermi-level (EF) pinning above the Dirac point. The work function of a single layer device increased steadily with increasing NO2 concentration indicating no change in reaction mechanism for high and low concentrations despite a change in sensor response direction. Epitaxially grown graphene device preparation is challenging due to poor adhesion of the graphene layer to the substrate. A field effect transistor (FET) device is presented which does not require wire bonding to contacts on graphene.
Materials Science Forum, 2012
ABSTRACT Recent research efforts in growth of 3C-SiC are reviewed. Sublimation growth is addresse... more ABSTRACT Recent research efforts in growth of 3C-SiC are reviewed. Sublimation growth is addressed with an emphasis on the enhanced understanding of polytype stability in relation to growth conditions, such as supersaturation and Si/C ratio. It is shown that at low temperature/supersaturation spiral 6H-SiC growth is favored, which prepares the surface for 3C-SiC nucleation. Provided the supersaturation is high enough, 3C-SiC nucleates as two-dimensional islands on terraces of the homoepitaxial 6H-SiC. Effect of different substrate surface preparations is considered. Typical extended defects and their electrical activity is discussed. Finally, possible novel applications are outlined.
Materials Science Forum, 2010
... Growth Des. Vol. 6 (2006) p. 2598 [13] P. Fiorenza, R. Lo Nigro, V. Raineri, S. Lombardo, RG ... more ... Growth Des. Vol. 6 (2006) p. 2598 [13] P. Fiorenza, R. Lo Nigro, V. Raineri, S. Lombardo, RG Toro, G. Malandrino and IL Fragalà, Appl. Phys. Lett. Vol. 87 (2005), p. 231913 [14] P. Fiorenza, R. Lo Nigro, V. Raineri and D. Salinas, Microelec. Eng. Vol. 84 (2007), p. 441 ...
![Research paper thumbnail of Impact of Morphological Features on the Dielectric Breakdown at SiO[sub 2]∕3C-SiC Interfaces](https://attachments.academia-assets.com/39434413/thumbnails/1.jpg)
](Thin SiO 2 layers were thermally grown onto cubic silicon carbide (3C-SiC) heteroepitaxial layers... more Thin SiO 2 layers were thermally grown onto cubic silicon carbide (3C-SiC) heteroepitaxial layers of different surface roughness and with different types of near-surface epitaxial defects. Localized dielectric breakdown (BD) was studied by electrically stressing the system using Conductive Atomic Force Microscopy (C-AFM), which constitutes a means to directly and simultaneously observe localized dielectric failure as a function of stress time and surface morphology with nanoscale lateral resolution. The BD kinetics was evaluated by fitting the experimental failure ratios as a function of stress time to the failure probability described by Weibull statistics, in turn allowing to distinguish between defect-induced (extrinsic) and intrinsic dielectric BD events. The results give useful information about how morphological features at the 3C-SiC surface influence the BD generation in thermally grown oxides on this polytype.
ABSTRACT In this paper, the evolution of the electrical characteristics of Pt Schottky contacts t... more ABSTRACT In this paper, the evolution of the electrical characteristics of Pt Schottky contacts to cubic silicon carbide (3CSiC) upon annealing was investigated. The Pt/3C-SiC system was structurally and electrically characterized upon annealing in the temperature range 500°C – 900°C. X-ray diffraction (XRD) showed the formation of platinum silicide (Pt2Si) starting at an annealing temperature of 500°C. After metal preparation, the current-voltage (I-V) characteristics of Pt/3C-SiC diodes exhibited a lower leakage current and a higher Schottky barrier height with respect to the previously studied Au/3C-SiC system [1]. A further improvement was observed after annealing at 500°C, and attributed to the consumption of a SiC surface-layer by the reaction, thus reducing the influence of the original interface states. On the other hand, annealing at higher temperatures (700°C and 900°C) caused a degradation of the contact properties, which can be related to the evolution of carbon clusters released during reaction.
Materials Science Forum, 2009
Abstract This paper reports on the macro-and nanoscale electro-structural evolution, as a functio... more Abstract This paper reports on the macro-and nanoscale electro-structural evolution, as a function of annealing temperature, of nickel-silicide Ohmic contacts to 3C-SiC, grown on 6H-SiC substrates by a Vapor-Liquid-Solid (VLS) technique. The structural and electrical ...
Scripta Materialia, 2015
We report a single-step procedure for growth of ohmic Ti 3 SiC 2 on 4H-SiC by sputter-deposition ... more We report a single-step procedure for growth of ohmic Ti 3 SiC 2 on 4H-SiC by sputter-deposition of Ti at 960°C, based on the Ti-SiC solid-state reaction during deposition. X-ray diffraction and electron microscopy show the growth of interfacial Ti 3 SiC 2 . The as-deposited contacts are ohmic, in contrast to multistep processes with deposition followed by rapid thermal annealing. This procedure also offers the possibility of direct synthesis of oxygen-barrier capping layers before exposure to air, potentially improving contact stability in high-temperature and high-power devices.
Solid State Phenomena, 2009
Page 1. Demonstration of defect-induced limitations on the properties of Au/3C-SiC Schottky barri... more Page 1. Demonstration of defect-induced limitations on the properties of Au/3C-SiC Schottky barrier diodes Jens Eriksson 1, 2, a , Ming-Hung Weng 1 , Fabrizio Roccaforte 1 , Filippo Giannazzo 1 , Stefano Leone 3 , Vito Raineri 1 ...
Materials Science Forum, 2010
Page 1. On the viability of Au/3C-SiC Schottky barrier diodes Jens Eriksson 1, 2,a , Ming-Hung We... more Page 1. On the viability of Au/3C-SiC Schottky barrier diodes Jens Eriksson 1, 2,a , Ming-Hung Weng 1 , Fabrizio Roccaforte 1 , Filippo Giannazzo 1 ,Salvatore Di Franco 1 , Stefano Leone 3 , Vito Raineri 1 1CNR-IMM, Strada VIII n. 5, Zona Industriale, 95121, Catania, Italy ...
Sensors and Actuators B: Chemical, 2009
Zinc oxide is an interesting material for bio and chemical sensors. It is a semiconducting metal ... more Zinc oxide is an interesting material for bio and chemical sensors. It is a semiconducting metal oxide with potential as an integrated multisensing sensor platform, which simultaneously detects parameters like change in field effect, mass and surface resistivity. In this investigation we have used resistive sensor measurements regarding the oxygen gas sensitivity in order to characterize sensing layers based on electrochemically produced ZnO nanoparticles and PE-MOCVD grown ZnO films. Proper annealing procedures were developed in order to get stable sensing properties and the oxygen sensitivity towards operation temperature was investigated. The ZnO nanoparticles showed a considerably increased response to oxygen as compared to the films. Preliminary investigations were also performed regarding the selectivity to other gases present in car exhausts or flue gases.
Physica B: Condensed Matter, 2014
ABSTRACT Graphene-based chemical gas sensors normally show ultra-high sensitivity to certain gas ... more ABSTRACT Graphene-based chemical gas sensors normally show ultra-high sensitivity to certain gas molecules but at the same time suffer from poor selectivity and slow response and recovery times. Several approaches based on functionalization or modification of the graphene surface have been demonstrated as means to improve these issues, but most such measures result in poor reproducibility. In this study we investigate reproducible graphene surface modifications by sputter deposition of thin nanostructured Au or Pt layers. It is demonstrated that under the right metallization conditions the electronic properties of the surface remain those of graphene, while the surface chemistry is modified to improve sensitivity, selectivity and speed of response to nitrogen dioxide.
Physica B: Condensed Matter, 2014
ABSTRACT We report on the structural and electronic properties of graphene grown on SiC by high-t... more ABSTRACT We report on the structural and electronic properties of graphene grown on SiC by high-temperature sublimation. We have studied thickness uniformity of graphene grown on 4H–SiC (0 0 0 1), 6H–SiC (0 0 0 1), and 3C–SiC (1 1 1) substrates and investigated in detail graphene surface morphology and electronic properties. Differences in the thickness uniformity of the graphene layers on different SiC polytypes is related mainly to the minimization of the terrace surface energy during the step bunching process. It is also shown that a lower substrate surface roughness results in more uniform step bunching and consequently better quality of the grown graphene. We have compared the three SiC polytypes with a clear conclusion in favor of 3C–SiC. Localized lateral variations in the Fermi energy of graphene are mapped by scanning Kelvin probe microscopy. It is found that the overall single-layer graphene coverage depends strongly on the surface terrace width, where a more homogeneous coverage is favored by wider terraces. It is observed that the step distance is a dominating, factor in determining the unintentional doping of graphene from the SiC substrate. Microfocal spectroscopic ellipsometry mapping of the electronic properties and thickness of epitaxial graphene on 3C–SiC (1 1 1) is also reported. Growth of one monolayer graphene is demonstrated on both Si- and C-polarity of the 3C–SiC substrates and it is shown that large area homogeneous single monolayer graphene can be achieved on the Si-face substrates. Correlations between the number of graphene monolayers on one hand and the main transition associated with an exciton enhanced van Hove singularity at ~4.5 eV and the free-charge carrier scattering time, on the other are established. It is shown that the interface structure on the Si- and C-polarity of the 3C–SiC (1 1 1) differs and has a determining role for the thickness and electronic properties homogeneity of the epitaxial graphene.
Nanoscale Research Letters, 2011
In this work, the transport properties of metal/3C-SiC interfaces were monitored employing a nano... more In this work, the transport properties of metal/3C-SiC interfaces were monitored employing a nanoscale characterization approach in combination with conventional electrical measurements. In particular, using conductive atomic force microscopy allowed demonstrating that the stacking fault is the most pervasive, electrically active extended defect at 3C-SiC(111) surfaces, and it can be electrically passivated by an ultraviolet irradiation treatment. For the Au/3C-SiC Schottky interface, a contact area dependence of the Schottky barrier height (Φ B ) was found even after this passivation, indicating that there are still some electrically active defects at the interface. Improved electrical properties were observed in the case of the Pt/3C-SiC system. In this case, annealing at 500°C resulted in a reduction of the leakage current and an increase of the Schottky barrier height (from 0.77 to 1.12 eV). A structural analysis of the reaction zone carried out by transmission electron microscopy [TEM] and X-ray diffraction showed that the improved electrical properties can be attributed to a consumption of the surface layer of SiC due to silicide (Pt 2 Si) formation. The degradation of Schottky characteristics at higher temperatures (up to 900°C) could be ascribed to the out-diffusion and aggregation of carbon into clusters, observed by TEM analysis.
![Research paper thumbnail of Nanoscale probing of dielectric breakdown at SiO[sub 2]/3C-SiC interfaces](https://attachments.academia-assets.com/39434381/thumbnails/1.jpg)
](Journal of Applied Physics, 2011
Thin ͑6-7 nm͒ SiO 2 layers were thermally grown onto cubic silicon carbide ͑3C-SiC͒ heteroepitaxi... more Thin ͑6-7 nm͒ SiO 2 layers were thermally grown onto cubic silicon carbide ͑3C-SiC͒ heteroepitaxial layers of different surface roughness and with different types of near-surface epitaxial defects. Localized dielectric breakdown ͑BD͒ was studied by electrically stressing the system using conductive atomic force microscopy ͑C-AFM͒, which constitutes a means to directly and simultaneously observe localized dielectric failure as a function of stress time and surface morphology with nanoscale lateral resolution. AFM and scanning capacitance microscopy ͑SCM͒ were used to monitor defects and the morphological and capacitive uniformities of the SiO 2 , respectively, while capacitance-voltage ͑C-V͒ measurements were used to evaluate the presence of charges and traps in the oxide layers. The BD kinetics was evaluated by fitting the experimental failure ratios as a function of the stress time to the failure probability described by Weibull statistics, in turn allowing a distinction to be made between defect-induced ͑extrinsic͒ and intrinsic dielectric BD events. The results give useful information about how morphological features at the 3C-SiC surface as well as trapped charges influence the BD generation in thermally grown oxides on this polytype.
Applied Physics Letters, 2009
We report on the evolution of the electrical and structural properties of contacts during anneali... more We report on the evolution of the electrical and structural properties of contacts during annealing in the temperature range of . A structural analysis showed the formation of different nickel silicide phases upon annealing. A combination of transmission line model and conductive atomic ...
Applied Physics Letters, 2012
High-temperature iridium-gated field effect transistors based on silicon carbide have been used f... more High-temperature iridium-gated field effect transistors based on silicon carbide have been used for sensitive detection of specific volatile organic compounds (VOCs) in concentrations of health concern, for indoor air quality monitoring and control. Formaldehyde, naphthalene, and benzene were studied as hazardous VOCs at parts per billion (ppb) down to sub-ppb levels. The sensor performance and characteristics were investigated at a constant temperature of 330 °C and at different levels of relative humidity up to 60%, showing good stability and repeatability of the sensor response, and excellent detection limits in the sub-ppb range.
2008 IEEE Sensors, 2008
In this work the effect of ambient influence on the electrical conductivity of ZnO films has been... more In this work the effect of ambient influence on the electrical conductivity of ZnO films has been studied. Nanostructured ZnO films (undoped and Ga, Co, Mn doped) were exposed to oxygen (1 -80 vol. %) at temperature range 300 -500 ºС. A dominant effect of ambient influence via oxygen absorption was observed: the intensity of conductivity decrease was found to be proportional with temperature and tends to saturation with time. After oxygen saturation the reversible effect of oxygen adsorption became dominant and contributed to the films conductivity. Oxygen exposed undoped ZnO films revealed high sensitivity for oxygen content change in the ambience, therefore they have been further processed for gas sensor fabrication.
Materials Science Forum, 2013
Large variations have been observed in the thickness uniformity and carrier concentration of epit... more Large variations have been observed in the thickness uniformity and carrier concentration of epitaxial graphene grown on SiC by sublimation for samples grown under identical conditions and on nominally on-axis hexagonal SiC (0001) substrates. We have previously shown that these issues are both related to the morphology of the graphene-SiC surface after sublimation growth.
Materials Science Forum, 2012
ABSTRACT Epitaxially grown single layer graphene on silicon carbide (SiC) resistive sensors were ... more ABSTRACT Epitaxially grown single layer graphene on silicon carbide (SiC) resistive sensors were characterised for NO2 response at room and elevated temperatures, with an n-p type transition observed with increasing NO2 concentration for all sensors. The concentration of NO2 required to cause this transition varied for different graphene samples and is attributed to varying degrees of substrate induced Fermi-level (EF) pinning above the Dirac point. The work function of a single layer device increased steadily with increasing NO2 concentration indicating no change in reaction mechanism for high and low concentrations despite a change in sensor response direction. Epitaxially grown graphene device preparation is challenging due to poor adhesion of the graphene layer to the substrate. A field effect transistor (FET) device is presented which does not require wire bonding to contacts on graphene.
Materials Science Forum, 2012
ABSTRACT Recent research efforts in growth of 3C-SiC are reviewed. Sublimation growth is addresse... more ABSTRACT Recent research efforts in growth of 3C-SiC are reviewed. Sublimation growth is addressed with an emphasis on the enhanced understanding of polytype stability in relation to growth conditions, such as supersaturation and Si/C ratio. It is shown that at low temperature/supersaturation spiral 6H-SiC growth is favored, which prepares the surface for 3C-SiC nucleation. Provided the supersaturation is high enough, 3C-SiC nucleates as two-dimensional islands on terraces of the homoepitaxial 6H-SiC. Effect of different substrate surface preparations is considered. Typical extended defects and their electrical activity is discussed. Finally, possible novel applications are outlined.
Materials Science Forum, 2010
... Growth Des. Vol. 6 (2006) p. 2598 [13] P. Fiorenza, R. Lo Nigro, V. Raineri, S. Lombardo, RG ... more ... Growth Des. Vol. 6 (2006) p. 2598 [13] P. Fiorenza, R. Lo Nigro, V. Raineri, S. Lombardo, RG Toro, G. Malandrino and IL Fragalà, Appl. Phys. Lett. Vol. 87 (2005), p. 231913 [14] P. Fiorenza, R. Lo Nigro, V. Raineri and D. Salinas, Microelec. Eng. Vol. 84 (2007), p. 441 ...
Thin SiO 2 layers were thermally grown onto cubic silicon carbide (3C-SiC) heteroepitaxial layers... more Thin SiO 2 layers were thermally grown onto cubic silicon carbide (3C-SiC) heteroepitaxial layers of different surface roughness and with different types of near-surface epitaxial defects. Localized dielectric breakdown (BD) was studied by electrically stressing the system using Conductive Atomic Force Microscopy (C-AFM), which constitutes a means to directly and simultaneously observe localized dielectric failure as a function of stress time and surface morphology with nanoscale lateral resolution. The BD kinetics was evaluated by fitting the experimental failure ratios as a function of stress time to the failure probability described by Weibull statistics, in turn allowing to distinguish between defect-induced (extrinsic) and intrinsic dielectric BD events. The results give useful information about how morphological features at the 3C-SiC surface influence the BD generation in thermally grown oxides on this polytype.
ABSTRACT In this paper, the evolution of the electrical characteristics of Pt Schottky contacts t... more ABSTRACT In this paper, the evolution of the electrical characteristics of Pt Schottky contacts to cubic silicon carbide (3CSiC) upon annealing was investigated. The Pt/3C-SiC system was structurally and electrically characterized upon annealing in the temperature range 500°C – 900°C. X-ray diffraction (XRD) showed the formation of platinum silicide (Pt2Si) starting at an annealing temperature of 500°C. After metal preparation, the current-voltage (I-V) characteristics of Pt/3C-SiC diodes exhibited a lower leakage current and a higher Schottky barrier height with respect to the previously studied Au/3C-SiC system [1]. A further improvement was observed after annealing at 500°C, and attributed to the consumption of a SiC surface-layer by the reaction, thus reducing the influence of the original interface states. On the other hand, annealing at higher temperatures (700°C and 900°C) caused a degradation of the contact properties, which can be related to the evolution of carbon clusters released during reaction.
Materials Science Forum, 2009
Abstract This paper reports on the macro-and nanoscale electro-structural evolution, as a functio... more Abstract This paper reports on the macro-and nanoscale electro-structural evolution, as a function of annealing temperature, of nickel-silicide Ohmic contacts to 3C-SiC, grown on 6H-SiC substrates by a Vapor-Liquid-Solid (VLS) technique. The structural and electrical ...
Scripta Materialia, 2015
We report a single-step procedure for growth of ohmic Ti 3 SiC 2 on 4H-SiC by sputter-deposition ... more We report a single-step procedure for growth of ohmic Ti 3 SiC 2 on 4H-SiC by sputter-deposition of Ti at 960°C, based on the Ti-SiC solid-state reaction during deposition. X-ray diffraction and electron microscopy show the growth of interfacial Ti 3 SiC 2 . The as-deposited contacts are ohmic, in contrast to multistep processes with deposition followed by rapid thermal annealing. This procedure also offers the possibility of direct synthesis of oxygen-barrier capping layers before exposure to air, potentially improving contact stability in high-temperature and high-power devices.
Solid State Phenomena, 2009
Page 1. Demonstration of defect-induced limitations on the properties of Au/3C-SiC Schottky barri... more Page 1. Demonstration of defect-induced limitations on the properties of Au/3C-SiC Schottky barrier diodes Jens Eriksson 1, 2, a , Ming-Hung Weng 1 , Fabrizio Roccaforte 1 , Filippo Giannazzo 1 , Stefano Leone 3 , Vito Raineri 1 ...
Materials Science Forum, 2010
Page 1. On the viability of Au/3C-SiC Schottky barrier diodes Jens Eriksson 1, 2,a , Ming-Hung We... more Page 1. On the viability of Au/3C-SiC Schottky barrier diodes Jens Eriksson 1, 2,a , Ming-Hung Weng 1 , Fabrizio Roccaforte 1 , Filippo Giannazzo 1 ,Salvatore Di Franco 1 , Stefano Leone 3 , Vito Raineri 1 1CNR-IMM, Strada VIII n. 5, Zona Industriale, 95121, Catania, Italy ...
Sensors and Actuators B: Chemical, 2009
Zinc oxide is an interesting material for bio and chemical sensors. It is a semiconducting metal ... more Zinc oxide is an interesting material for bio and chemical sensors. It is a semiconducting metal oxide with potential as an integrated multisensing sensor platform, which simultaneously detects parameters like change in field effect, mass and surface resistivity. In this investigation we have used resistive sensor measurements regarding the oxygen gas sensitivity in order to characterize sensing layers based on electrochemically produced ZnO nanoparticles and PE-MOCVD grown ZnO films. Proper annealing procedures were developed in order to get stable sensing properties and the oxygen sensitivity towards operation temperature was investigated. The ZnO nanoparticles showed a considerably increased response to oxygen as compared to the films. Preliminary investigations were also performed regarding the selectivity to other gases present in car exhausts or flue gases.
Physica B: Condensed Matter, 2014
ABSTRACT Graphene-based chemical gas sensors normally show ultra-high sensitivity to certain gas ... more ABSTRACT Graphene-based chemical gas sensors normally show ultra-high sensitivity to certain gas molecules but at the same time suffer from poor selectivity and slow response and recovery times. Several approaches based on functionalization or modification of the graphene surface have been demonstrated as means to improve these issues, but most such measures result in poor reproducibility. In this study we investigate reproducible graphene surface modifications by sputter deposition of thin nanostructured Au or Pt layers. It is demonstrated that under the right metallization conditions the electronic properties of the surface remain those of graphene, while the surface chemistry is modified to improve sensitivity, selectivity and speed of response to nitrogen dioxide.
Physica B: Condensed Matter, 2014
ABSTRACT We report on the structural and electronic properties of graphene grown on SiC by high-t... more ABSTRACT We report on the structural and electronic properties of graphene grown on SiC by high-temperature sublimation. We have studied thickness uniformity of graphene grown on 4H–SiC (0 0 0 1), 6H–SiC (0 0 0 1), and 3C–SiC (1 1 1) substrates and investigated in detail graphene surface morphology and electronic properties. Differences in the thickness uniformity of the graphene layers on different SiC polytypes is related mainly to the minimization of the terrace surface energy during the step bunching process. It is also shown that a lower substrate surface roughness results in more uniform step bunching and consequently better quality of the grown graphene. We have compared the three SiC polytypes with a clear conclusion in favor of 3C–SiC. Localized lateral variations in the Fermi energy of graphene are mapped by scanning Kelvin probe microscopy. It is found that the overall single-layer graphene coverage depends strongly on the surface terrace width, where a more homogeneous coverage is favored by wider terraces. It is observed that the step distance is a dominating, factor in determining the unintentional doping of graphene from the SiC substrate. Microfocal spectroscopic ellipsometry mapping of the electronic properties and thickness of epitaxial graphene on 3C–SiC (1 1 1) is also reported. Growth of one monolayer graphene is demonstrated on both Si- and C-polarity of the 3C–SiC substrates and it is shown that large area homogeneous single monolayer graphene can be achieved on the Si-face substrates. Correlations between the number of graphene monolayers on one hand and the main transition associated with an exciton enhanced van Hove singularity at ~4.5 eV and the free-charge carrier scattering time, on the other are established. It is shown that the interface structure on the Si- and C-polarity of the 3C–SiC (1 1 1) differs and has a determining role for the thickness and electronic properties homogeneity of the epitaxial graphene.
Nanoscale Research Letters, 2011
In this work, the transport properties of metal/3C-SiC interfaces were monitored employing a nano... more In this work, the transport properties of metal/3C-SiC interfaces were monitored employing a nanoscale characterization approach in combination with conventional electrical measurements. In particular, using conductive atomic force microscopy allowed demonstrating that the stacking fault is the most pervasive, electrically active extended defect at 3C-SiC(111) surfaces, and it can be electrically passivated by an ultraviolet irradiation treatment. For the Au/3C-SiC Schottky interface, a contact area dependence of the Schottky barrier height (Φ B ) was found even after this passivation, indicating that there are still some electrically active defects at the interface. Improved electrical properties were observed in the case of the Pt/3C-SiC system. In this case, annealing at 500°C resulted in a reduction of the leakage current and an increase of the Schottky barrier height (from 0.77 to 1.12 eV). A structural analysis of the reaction zone carried out by transmission electron microscopy [TEM] and X-ray diffraction showed that the improved electrical properties can be attributed to a consumption of the surface layer of SiC due to silicide (Pt 2 Si) formation. The degradation of Schottky characteristics at higher temperatures (up to 900°C) could be ascribed to the out-diffusion and aggregation of carbon into clusters, observed by TEM analysis.
Journal of Applied Physics, 2011
Thin ͑6-7 nm͒ SiO 2 layers were thermally grown onto cubic silicon carbide ͑3C-SiC͒ heteroepitaxi... more Thin ͑6-7 nm͒ SiO 2 layers were thermally grown onto cubic silicon carbide ͑3C-SiC͒ heteroepitaxial layers of different surface roughness and with different types of near-surface epitaxial defects. Localized dielectric breakdown ͑BD͒ was studied by electrically stressing the system using conductive atomic force microscopy ͑C-AFM͒, which constitutes a means to directly and simultaneously observe localized dielectric failure as a function of stress time and surface morphology with nanoscale lateral resolution. AFM and scanning capacitance microscopy ͑SCM͒ were used to monitor defects and the morphological and capacitive uniformities of the SiO 2 , respectively, while capacitance-voltage ͑C-V͒ measurements were used to evaluate the presence of charges and traps in the oxide layers. The BD kinetics was evaluated by fitting the experimental failure ratios as a function of the stress time to the failure probability described by Weibull statistics, in turn allowing a distinction to be made between defect-induced ͑extrinsic͒ and intrinsic dielectric BD events. The results give useful information about how morphological features at the 3C-SiC surface as well as trapped charges influence the BD generation in thermally grown oxides on this polytype.
Applied Physics Letters, 2009
We report on the evolution of the electrical and structural properties of contacts during anneali... more We report on the evolution of the electrical and structural properties of contacts during annealing in the temperature range of . A structural analysis showed the formation of different nickel silicide phases upon annealing. A combination of transmission line model and conductive atomic ...
Applied Physics Letters, 2012