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in subjects: "Bandgap"

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Novel High Efficiency Photovoltaic Devices Based on the III-N Material System: Final Technical Report, 7 December 2005 - 29 August 2008

The research shows that InGaN material system can be used to realize high-efficiency solar cells, making contributions to growth, modeling, understanding of loss mechanisms, and process optimization.

Date: October 1, 2008

Creator: Hornsberg, C.; Doolittle, W. A. & Ferguson, I.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Enhanced-Depletion-Width GaInNAs Solar Cells Grown by Molecular-Beam Epitaxy

GaInNAs, potentially useful in a 4-junction GaInP2/GaAs/GaInNAs/Ge solar cell, suffers from very low minority-carrier collection lengths. To date, the currents available from GaInNAs solar cells are not high enough to increase the efficiency of a 3-junction device by adding this fourth junction. Here, we grow p-i-n GaInNAs solar cells by molecular-beam epitaxy with wide, intrinsic base layers and internal quantum efficiencies near 1.0. If similar 1.0-eV GaInNAs junctions can be successfully int… more

Date: February 1, 2005

Creator: Ptak, A. J.; Friedman, D. J.; Kurtz, S. & Kiehl, J.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Technical Progress Report for "Optical and Electrical Properties of III-Nitrides and Related Materials"

Investigations have been conducted focused on the fundamental material properties of AIN and high AI-content AIGaN alloys and further developed MOCVD growth technologies for obtaining these materials with improved crystalline quality and conductivities.

Date: October 31, 2008

Creator: Jiang, Hongxing

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Processing Materials Devices and Diagnostics for Thin Film Photovoltaics: Fundamental and Manufacturability Issues; Final Report, 5 September 2001 - 31 May 2008

The critical issues addressed in this study on CIGS, CdTe, and a-Si modules will provide the science and engineering basis for developing viable commercial processes and improved module performance.

Date: April 1, 2009

Creator: Birkmire, R. W.; Shafarman, W. N.; Eser, E.; Hegedus, S. S.; McCandless, B. E.; Dobson, K. D. et al.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

NREL Spurred the Success of Multijunction Solar Cells (Fact Sheet)

Many scientists once believed that high-quality gallium indium phosphide (GaInP) alloys could not be grown for use as semiconductors because the alloys would separate. However, researchers at the National Renewable Energy Laboratory (NREL) thought differently, and they employed GaInP in a material combination that allowed the multijunction cell to flourish. The multijunction cell is now the workhorse that powers satellites and the catalyst for renewed interest in concentrator photovoltaic produ… more

Date: August 1, 2013

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

0.7-eV GaInAs Junction for a GaInP/GaAs/GaInAs(1-eV)/GaInAs(0.7-eV) Four-Junction Solar Cell: Preprint

We discuss recent developments in III-V multijunction solar cells, focusing on adding a fourth junction to the Ga0.5In0.5P/GaAs/Ga0.75In0.25As inverted three-junction cell. This cell, grown inverted on GaAs so that the lattice-mismatched Ga0.75In0.25As third junction is the last one grown, has demonstrated 38% efficiency, and 40% is likely in the near future. To achieve still further gains, a lower-bandgap GaxIn1-xAs fourth junction could be added to the three-junction structure for a four-junc… more

Date: May 1, 2006

Creator: Friedman, D. J.; Geisz, J. F.; Norman, A. G.; Wanlass, M. W. & Kurtz, S. R.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Investigation of Cd1-XMgxTe Alloys for Tandem Solar Cell Applications: Preprint

Theoretical modeling of two-junction tandem solar cells shows that for optimal device performance, the bandgap of the top cell should be in the range of 1.6 to 1.8 eV. Cd1-xMgxTe (CMT) alloys have a lattice constant close to that of CdTe, and the addition of a small amount of Mg changes the bandgap considerably. In this paper, we present our work on developing CMT for solar cell applications. CMT films were prepared by vacuum deposition with co-evaporation of CdTe and Mg on substrates heated to… more

Date: May 1, 2006

Creator: Dhere, R.; Ramanathan, K.; Scharf, J.; Moutinho, H.; To, B.; Duda, A. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Hybrid Nanorod-Polymer Solar Cell: Final Report; 19 July 1999--19 September 2002

With the support of this grant, we successfully demonstrated that semiconductor nanorods can be used to fabricate readily processed and efficient hybrid solar cells together with polymers. By controlling nanorod length, we changed the distance over which electrons are transported directly through the thin-film device. Tuning the bandgap by altering the nanorod radius enabled us to optimize the overlap between the absorption spectrum of the cell and the solar emission spectrum. A photovoltaic de… more

Date: August 1, 2003

Creator: Alivisatos, A. P.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Growth and Characterization of GaN As(P) for High Efficiency Solar Cells: Final Subcontract Report, 29 July 1999--28 September 2003

This report describes the characterization of GaAs1-xNx and GaP1-xNx alloys using scanning tunneling microscopy (STM) and ballistic electron emission microscopy (BEEM). One objective was to understand the origins of the giant bandgap bowing of these compound semiconductor alloys as a function of nitrogen concentration. The STM and BEEM have been used to characterize GaNxAs1-x and GaNxP1-x as a function of composition. The reduction in bandgap has been measured. Detailed studies of the band stru… more

Date: June 1, 2004

Creator: Narayanamurti, V.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Novel Capacitance Measurements in Copper Indium Gallium Diselenide Alloys: Final Subcontract Report, 1 July 1999--31 August 2003

This subcontract report describes the University of Oregon's objectives to measure the electronic properties of the copper indium/gallium diselenide alloys using several well-developed capacitance techniques appropriate for probing materials with a continuous distribution of semiconducting gap electronic energy states. We applied a new synthetic method to the production of CIGS alloys, namely, the modulated elemental reactant method. To form CIGS by this method, alternating layers of Cu:In:Se a… more

Date: May 1, 2004

Creator: Johnson, D. C.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Investigation of CdZnTe for Thin-Film Tandem Solar Cell Applications: Preprint

Modeling of two-junction tandem devices shows that for optimal device performance, the bandgap of the top cell should be around 1.6-1.8 eV. CdZnTe alloys can be tailored to yield bandgaps in the desired range. In this study, we considered were used to fabricate these films, using close-spaced sublimation (CSS) and radio-frequency sputtering (RFS) techniques. In the first approach, we used mixed powders of CdTe and ZnTe as the source for film deposition by CSS. Even for the ZnTe/CdTe (95:5 ratio… more

Date: April 1, 2003

Creator: Dhere, R.; Gessert, T.; Zhou, J.; Asher, S.; Pankow, J. & Moutinho, H.

Item Type: Article

Partner: UNT Libraries Government Documents Department