Samantha Cruz - Academia.edu (original) (raw)

Papers by Samantha Cruz

Research paper thumbnail of Development of IMM-α and Z4J Radiation Hard III-V Solar Cells

2018 IEEE 7th World Conference on Photovoltaic Energy Conversion (WCPEC) (A Joint Conference of 45th IEEE PVSC, 28th PVSEC & 34th EU PVSEC)

Research paper thumbnail of Textured III-V Semiconductor

Research paper thumbnail of Temperature-Dependent Carrier Transport in a p-GaN/i-InGaN/n-GaN Solar Cell Heterostructure using Ultrafast Spectroscopy

CLEO: 2013, 2013

ABSTRACT Temperature-dependent carrier transport is investigated using ultrafast spectroscopy in ... more ABSTRACT Temperature-dependent carrier transport is investigated using ultrafast spectroscopy in a p-GaN/i-InGaN/n-GaN solar cell with heavily-doped layers to compensate for polarization charges at the heterointerface. We observe a flip in the transport direction at 110 K.

Research paper thumbnail of Integrated non-III-nitride/III-nitride tandem solar cell

69th Device Research Conference, 2011

ABSTRACT III-nitrides have recently been demonstrated as potential photovoltaic device material p... more ABSTRACT III-nitrides have recently been demonstrated as potential photovoltaic device material particularly in the high-energy portion of the solar spectrum. The large lattice mismatch between InN and GaN however, makes it difficult to grow good quality high In-composition InGaN films for low bandgap subcells. The integration of III-N based solar cells, which have currently been demonstrated to work well above 2.0 eV, with mature IV and III-V based solar cell technologies, which work well at bandgaps ≤ 2.0 eV, has the potential to improve the efficiency of current multi-junction solar cells. In this paper, we present the first on-wafer integration of InGaN/GaN solar cells with non-III-nitride (GaAs) solar cells.

Research paper thumbnail of Optical and thermal properties of In<inf>12</inf>Ga<inf>88</inf>N/GaN solar cells

2009 34th IEEE Photovoltaic Specialists Conference (PVSC), 2009

In this work we investigate the optical and thermal properties of In12Ga88N/GaN photovoltaic devi... more In this work we investigate the optical and thermal properties of In12Ga88N/GaN photovoltaic devices. These devices show very good solar cell characteristics with peak external quantum efficiency of 63%, open circuit voltage of 1.7 V, and a fill factor of 76%. Thermal measurements show no reduction in output power with increasing temperature up to 87°C.

Research paper thumbnail of <title>Optical absorption and transient photobleaching in solutions of surfactant-encapsulated and DNA-wrapped single-walled carbon nanotubes</title>

Quantum Sensing and Nanophotonic Devices, 2004

Optical absorption and transient photobleaching in solutions of surfactant encapsulated and DNA w... more Optical absorption and transient photobleaching in solutions of surfactant encapsulated and DNA wrapped single-walled carbon nanotubes (SWNTs) are studied. Optical transitions between van Hove singularities are red shifted in solutions of DNA wrapped SWNTs compared with transitions in solutions of sodium dodecyl sulfate (SDS) encapsulated SWNTs. This red shift may be due to changes in the local surrounding dielectric constant

Research paper thumbnail of Optimization of the p-GaN window layer for InGaN/GaN solar cells

2010 35th IEEE Photovoltaic Specialists Conference, 2010

In this work we report on the optimization of the p-GaN window layer for InGaN/GaN solar cells. W... more In this work we report on the optimization of the p-GaN window layer for InGaN/GaN solar cells. We studied the effect of p-GaN thickness and growth temperature on the electrical performance. By optimizing the window thickness of InxGa1-xN solar cells with XIn ≈ 0.04 we maximized short wavelength response and produced solar cells with 82% FF and Voc of 2 V and enhancement of Jsc of 80% over un-optimized devices. We also studied the effect of growth temperature of the window layer, and found that the electrical performance was greatly improved with higher growth temperatures. By increasing the p-GaN growth temperature from 890°C to 1040°C, reverse bias leakage was reduced by three orders of magnitude, Voc increased from 0.85 to 1.65 V and peak output power increased by nearly 100% for devices with XIn ≈ 0.08. Surface pit density was also significantly decreased by increasing growth temperature and seems to be an important mechanism for leakage in these devices.

Research paper thumbnail of LASERS, OPTICS, AND OPTOELECTRONICS 021101 Directional single mode quantum cascade laser emission using second-order metal grating coupler (3 pages)

Research paper thumbnail of Effects of piezoelectric fields on optoelectronic properties of InGaN/GaN quantum-well light-emitting diodes prepared on nonpolar (1 0 \bar1 0) and semipolar (1 1 \bar{2} 2) orientations

Journal of Physics D: Applied Physics, 2009

Optical and electrical characteristics of InGaN/GaN quantum-well (QW) light-emitting diodes (LEDs... more Optical and electrical characteristics of InGaN/GaN quantum-well (QW) light-emitting diodes (LEDs) are the subjects of this study. Samples were prepared on nonpolar (1 0 &amp;amp;bar1 ; 0) and semipolar (1 1 &amp;amp;bar2 ; 2) orientations of bulk GaN substrates. Electrical-bias-applied ...

Research paper thumbnail of Geometrical Characteristics and Surface Polarity of Inclined Crystallographic Planes of the Wurtzite and Zincblende Structures

Journal of Electronic Materials, 2009

Inclined crystallographic planes of the wurtzite structure were investigated in comparison with t... more Inclined crystallographic planes of the wurtzite structure were investigated in comparison with the zincblende structure in terms of surface geometry characteristics. The ball-stick model indicates that the semipolar 1 " 101 À Á surface possesses a surface polarity resembling the anion polarity, which agrees with the common experimental observations of epitaxial growth preference for the cation-polarity 1 " 10 " 1 À Á surface over the 1 " 101 À Á surface. The wurtzite 11 " 22 È É surface was found to share geometrical similarities with the zincblende {100} surface uniquely among the possible semipolar planes. This finding encourages epitaxial growth on the 11 " 22 È É plane of wurtzite semiconductors, e.g., GaN, with the potential of avoiding atomic step formations typically associated with off-axis crystallographic planes.

Research paper thumbnail of Observation of positive thermal power coefficient in InGaN/GaN quantum well solar cells

Applied Physics Letters, 2011

... CJ Neufeld, SC Cruz, RM Farrell, M. Iza, JR Lang, S. Keller, S. Nakamura, SP DenBaars, JS Spe... more ... CJ Neufeld, SC Cruz, RM Farrell, M. Iza, JR Lang, S. Keller, S. Nakamura, SP DenBaars, JS Speck, and UK Mishra, Appl. ... RM Farrell, CJ Neufeld, SC Cruz, JR Lang, M. Iza, S. Keller, S. Nakamura, SP DenBaars, UK Mishra, and JS Speck, Appl. Phys. Lett. 98, 201107 (2011). ...

Research paper thumbnail of Effect of doping and polarization on carrier collection in InGaN quantum well solar cells

Applied Physics Letters, 2011

Page 1. Effect of doping and polarization on carrier collection in InGaN quantum well solar cells... more Page 1. Effect of doping and polarization on carrier collection in InGaN quantum well solar cells Carl J. Neufeld,1,a) Samantha C. Cruz,2 Robert M. Farrell,2 Michael Iza,2 Jordan R. Lang,2 Stacia Keller,1 Shuji Nakamura,2 Steven ...

Research paper thumbnail of High internal and external quantum efficiency InGaN/GaN solar cells

Applied Physics Letters, 2011

Research paper thumbnail of Effect of quantum well cap layer thickness on the microstructure and performance of InGaN/GaN solar cells

Applied Physics Letters, 2012

ABSTRACT

Research paper thumbnail of High quantum efficiency InGaN/GaN solar cells with 2.95 eV band gap

Applied Physics …, 2008

[Applied Physics Letters 93, 143502 (2008)]. Carl J. Neufeld, Nikholas G. Toledo, Samantha C. Cru... more [Applied Physics Letters 93, 143502 (2008)]. Carl J. Neufeld, Nikholas G. Toledo, Samantha C. Cruz, Michael Iza, Steven P. DenBaars, Umesh K. Mishra. Abstract. ... (Weinheim, Ger.) 12, 1571 (2000). X.Zhang, X.Wang, H.Xiao, C.Yang, J.Ran, C.Wang, Q.Hou, and JLLi, J. Phys. ...

Research paper thumbnail of InGaN-Based Solar Cells and High-Performance Broadband Optical Coatings for Ultrahigh Efficiency Hybrid Multijunction Device Designs

CLEO: 2013, 2013

ABSTRACT Efficiencies exceeding 40% have already been achieved with GaAs-based multijunction (MJ)... more ABSTRACT Efficiencies exceeding 40% have already been achieved with GaAs-based multijunction (MJ) solar cells. In this talk, we will discuss the unique advantages and challenges of fabricating hybrid InGaN-GaAs MJ cells for ultrahigh efficiency device designs.

Research paper thumbnail of High quantum efficiency InGaN/GaN multiple quantum well solar cells with spectral response extending out to 520 nm

Applied Physics Letters, 2011

We demonstrate high quantum efficiency InGaN/GaN multiple quantum well (QW) solar cells with spec... more We demonstrate high quantum efficiency InGaN/GaN multiple quantum well (QW) solar cells with spectral response extending out to 520 nm. Increasing the number of QWs in the active region did not reduce the carrier collection efficiency for devices with 10, 20, and 30 QWs. Solar ...

Research paper thumbnail of Development of IMM-α and Z4J Radiation Hard III-V Solar Cells

2018 IEEE 7th World Conference on Photovoltaic Energy Conversion (WCPEC) (A Joint Conference of 45th IEEE PVSC, 28th PVSEC & 34th EU PVSEC)

Research paper thumbnail of Textured III-V Semiconductor

Research paper thumbnail of Temperature-Dependent Carrier Transport in a p-GaN/i-InGaN/n-GaN Solar Cell Heterostructure using Ultrafast Spectroscopy

CLEO: 2013, 2013

ABSTRACT Temperature-dependent carrier transport is investigated using ultrafast spectroscopy in ... more ABSTRACT Temperature-dependent carrier transport is investigated using ultrafast spectroscopy in a p-GaN/i-InGaN/n-GaN solar cell with heavily-doped layers to compensate for polarization charges at the heterointerface. We observe a flip in the transport direction at 110 K.

Research paper thumbnail of Integrated non-III-nitride/III-nitride tandem solar cell

69th Device Research Conference, 2011

ABSTRACT III-nitrides have recently been demonstrated as potential photovoltaic device material p... more ABSTRACT III-nitrides have recently been demonstrated as potential photovoltaic device material particularly in the high-energy portion of the solar spectrum. The large lattice mismatch between InN and GaN however, makes it difficult to grow good quality high In-composition InGaN films for low bandgap subcells. The integration of III-N based solar cells, which have currently been demonstrated to work well above 2.0 eV, with mature IV and III-V based solar cell technologies, which work well at bandgaps ≤ 2.0 eV, has the potential to improve the efficiency of current multi-junction solar cells. In this paper, we present the first on-wafer integration of InGaN/GaN solar cells with non-III-nitride (GaAs) solar cells.

Research paper thumbnail of Optical and thermal properties of In<inf>12</inf>Ga<inf>88</inf>N/GaN solar cells

2009 34th IEEE Photovoltaic Specialists Conference (PVSC), 2009

In this work we investigate the optical and thermal properties of In12Ga88N/GaN photovoltaic devi... more In this work we investigate the optical and thermal properties of In12Ga88N/GaN photovoltaic devices. These devices show very good solar cell characteristics with peak external quantum efficiency of 63%, open circuit voltage of 1.7 V, and a fill factor of 76%. Thermal measurements show no reduction in output power with increasing temperature up to 87°C.

Research paper thumbnail of <title>Optical absorption and transient photobleaching in solutions of surfactant-encapsulated and DNA-wrapped single-walled carbon nanotubes</title>

Quantum Sensing and Nanophotonic Devices, 2004

Optical absorption and transient photobleaching in solutions of surfactant encapsulated and DNA w... more Optical absorption and transient photobleaching in solutions of surfactant encapsulated and DNA wrapped single-walled carbon nanotubes (SWNTs) are studied. Optical transitions between van Hove singularities are red shifted in solutions of DNA wrapped SWNTs compared with transitions in solutions of sodium dodecyl sulfate (SDS) encapsulated SWNTs. This red shift may be due to changes in the local surrounding dielectric constant

Research paper thumbnail of Optimization of the p-GaN window layer for InGaN/GaN solar cells

2010 35th IEEE Photovoltaic Specialists Conference, 2010

In this work we report on the optimization of the p-GaN window layer for InGaN/GaN solar cells. W... more In this work we report on the optimization of the p-GaN window layer for InGaN/GaN solar cells. We studied the effect of p-GaN thickness and growth temperature on the electrical performance. By optimizing the window thickness of InxGa1-xN solar cells with XIn ≈ 0.04 we maximized short wavelength response and produced solar cells with 82% FF and Voc of 2 V and enhancement of Jsc of 80% over un-optimized devices. We also studied the effect of growth temperature of the window layer, and found that the electrical performance was greatly improved with higher growth temperatures. By increasing the p-GaN growth temperature from 890°C to 1040°C, reverse bias leakage was reduced by three orders of magnitude, Voc increased from 0.85 to 1.65 V and peak output power increased by nearly 100% for devices with XIn ≈ 0.08. Surface pit density was also significantly decreased by increasing growth temperature and seems to be an important mechanism for leakage in these devices.

Research paper thumbnail of LASERS, OPTICS, AND OPTOELECTRONICS 021101 Directional single mode quantum cascade laser emission using second-order metal grating coupler (3 pages)

Research paper thumbnail of Effects of piezoelectric fields on optoelectronic properties of InGaN/GaN quantum-well light-emitting diodes prepared on nonpolar (1 0 \bar1 0) and semipolar (1 1 \bar{2} 2) orientations

Journal of Physics D: Applied Physics, 2009

Optical and electrical characteristics of InGaN/GaN quantum-well (QW) light-emitting diodes (LEDs... more Optical and electrical characteristics of InGaN/GaN quantum-well (QW) light-emitting diodes (LEDs) are the subjects of this study. Samples were prepared on nonpolar (1 0 &amp;amp;bar1 ; 0) and semipolar (1 1 &amp;amp;bar2 ; 2) orientations of bulk GaN substrates. Electrical-bias-applied ...

Research paper thumbnail of Geometrical Characteristics and Surface Polarity of Inclined Crystallographic Planes of the Wurtzite and Zincblende Structures

Journal of Electronic Materials, 2009

Inclined crystallographic planes of the wurtzite structure were investigated in comparison with t... more Inclined crystallographic planes of the wurtzite structure were investigated in comparison with the zincblende structure in terms of surface geometry characteristics. The ball-stick model indicates that the semipolar 1 " 101 À Á surface possesses a surface polarity resembling the anion polarity, which agrees with the common experimental observations of epitaxial growth preference for the cation-polarity 1 " 10 " 1 À Á surface over the 1 " 101 À Á surface. The wurtzite 11 " 22 È É surface was found to share geometrical similarities with the zincblende {100} surface uniquely among the possible semipolar planes. This finding encourages epitaxial growth on the 11 " 22 È É plane of wurtzite semiconductors, e.g., GaN, with the potential of avoiding atomic step formations typically associated with off-axis crystallographic planes.

Research paper thumbnail of Observation of positive thermal power coefficient in InGaN/GaN quantum well solar cells

Applied Physics Letters, 2011

... CJ Neufeld, SC Cruz, RM Farrell, M. Iza, JR Lang, S. Keller, S. Nakamura, SP DenBaars, JS Spe... more ... CJ Neufeld, SC Cruz, RM Farrell, M. Iza, JR Lang, S. Keller, S. Nakamura, SP DenBaars, JS Speck, and UK Mishra, Appl. ... RM Farrell, CJ Neufeld, SC Cruz, JR Lang, M. Iza, S. Keller, S. Nakamura, SP DenBaars, UK Mishra, and JS Speck, Appl. Phys. Lett. 98, 201107 (2011). ...

Research paper thumbnail of Effect of doping and polarization on carrier collection in InGaN quantum well solar cells

Applied Physics Letters, 2011

Page 1. Effect of doping and polarization on carrier collection in InGaN quantum well solar cells... more Page 1. Effect of doping and polarization on carrier collection in InGaN quantum well solar cells Carl J. Neufeld,1,a) Samantha C. Cruz,2 Robert M. Farrell,2 Michael Iza,2 Jordan R. Lang,2 Stacia Keller,1 Shuji Nakamura,2 Steven ...

Research paper thumbnail of High internal and external quantum efficiency InGaN/GaN solar cells

Applied Physics Letters, 2011

Research paper thumbnail of Effect of quantum well cap layer thickness on the microstructure and performance of InGaN/GaN solar cells

Applied Physics Letters, 2012

ABSTRACT

Research paper thumbnail of High quantum efficiency InGaN/GaN solar cells with 2.95 eV band gap

Applied Physics …, 2008

[Applied Physics Letters 93, 143502 (2008)]. Carl J. Neufeld, Nikholas G. Toledo, Samantha C. Cru... more [Applied Physics Letters 93, 143502 (2008)]. Carl J. Neufeld, Nikholas G. Toledo, Samantha C. Cruz, Michael Iza, Steven P. DenBaars, Umesh K. Mishra. Abstract. ... (Weinheim, Ger.) 12, 1571 (2000). X.Zhang, X.Wang, H.Xiao, C.Yang, J.Ran, C.Wang, Q.Hou, and JLLi, J. Phys. ...

Research paper thumbnail of InGaN-Based Solar Cells and High-Performance Broadband Optical Coatings for Ultrahigh Efficiency Hybrid Multijunction Device Designs

CLEO: 2013, 2013

ABSTRACT Efficiencies exceeding 40% have already been achieved with GaAs-based multijunction (MJ)... more ABSTRACT Efficiencies exceeding 40% have already been achieved with GaAs-based multijunction (MJ) solar cells. In this talk, we will discuss the unique advantages and challenges of fabricating hybrid InGaN-GaAs MJ cells for ultrahigh efficiency device designs.

Research paper thumbnail of High quantum efficiency InGaN/GaN multiple quantum well solar cells with spectral response extending out to 520 nm

Applied Physics Letters, 2011

We demonstrate high quantum efficiency InGaN/GaN multiple quantum well (QW) solar cells with spec... more We demonstrate high quantum efficiency InGaN/GaN multiple quantum well (QW) solar cells with spectral response extending out to 520 nm. Increasing the number of QWs in the active region did not reduce the carrier collection efficiency for devices with 10, 20, and 30 QWs. Solar ...