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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