Comparison of Dominant Electron Trap Levels in n-Type and p-Type GaAsN Using Deep-Level Transient Spectroscopy

Research output: Contribution to conferencePaper

Abstract

Higher-efficiency solar cells improve the likelihood that concentrator photovoltaic systems will become cost effective. A four-junction GaAs- and Ge-based solar cell incorporating a 1-eV bandgap material has an ideal AM0 efficiency of~40% and could also be used in a terrestrial concentrator module. The dilute-N GaAsN alloy's bandgap can be reduced to near 1 eV when the nitrogen content is 2% -3%. Indium can also be added to the alloy to improve lattice matching to GaAs and Ge. We have used deep-level transient spectroscopy (DLTS) to characterize traps in both p-type and n-type GaAsN. For each type of material, the dominant DLTS signal corresponds to an electron trap having an activation energy of about 0.35 eV for p-type GaAsN and about 0.45 eV for n-type GaAsN. In both types ofmaterials, the trap concentrations, modified by ..lambda..-effect factors, increase with both increasing N content and increased doping.
Original languageAmerican English
Number of pages5
StatePublished - 2005
Event2005 DOE Solar Energy Technologies Program Review Meeting - Denver, Colorado
Duration: 7 Nov 200510 Nov 2005

Conference

Conference2005 DOE Solar Energy Technologies Program Review Meeting
CityDenver, Colorado
Period7/11/0510/11/05

Bibliographical note

Presented at the 2005 DOE Solar Energy Technologies Program Review Meeting held November 7-10, 2005 in Denver, Colorado. Also included in the proceedings available on CD-ROM (DOE/GO-102006-2245; NREL/CD-520-38557)

NREL Publication Number

  • NREL/CP-520-38916

Keywords

  • GaAsN
  • NREL
  • photovoltaics (PV)
  • PV
  • solar
  • transient spectroscopy

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