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Hydrogen passivation of N(+)-P and P(+)-N heteroepitaxial InP solar cell structuresDislocations and related point defect complexes caused by lattice mismatch currently limit the performance of heteroepitaxial InP cells by introducing shunting paths across the active junction and by the formation of deep traps within the base region. We have previously demonstrated that plasma hydrogenation is an effective and stable means to passivate the electrical activity of such defects in specially designed heteroepitaxial InP test structures to probe hydrogen passivation at typical base depths within a cell structure. In this work, we present our results on the hydrogen passivation of actual heteroepitaxial n-p and p-n InP cell structures grown on GaAs substrates by metalorganic chemical vapor deposition (MOCVD). We have found that a 2 hour exposure to a 13.56 MHz hydrogen plasma at 275 C reduces the deep level concentration in the base regions of both n(+)-p and p(+)-n heteroepitaxial InP cell structures from as-grown values of 5-7 x 10(exp 14) cm(exp -3), down to 3-5 x 10(exp 12) cm(exp -3). All dopants were successfully reactivated by a 400 C, 5 minute anneal with no detectable activation of deep levels. One to five analysis indicated a subsequent approximately 100 fold decrease in reverse leakage current at -1 volt reverse bias, and an improved built in voltage for the p(+)-n structures. In addition to being passivated, dislocations are also shown to participate in secondary interactions during hydrogenation. We find that the presence of dislocations enhances hydrogen diffusion into the cell structure, and lowers the apparent dissociation energy of Zn-H complexes from 1.19 eV for homoepitaxial Zn-doped InP to 1.12 eV for heteroepitaxial Zn-doped InP. This is explained by additional hydrogen trapping at dislocations subsequent to the reactivation of Zn dopants after hydrogenation.
Document ID
19960045582
Document Type
Conference Paper
Authors
Chatterjee, Basab (Ohio State Univ. Columbus, OH United States)
Davis, William C. (Ohio State Univ. Columbus, OH United States)
Ringel, Steve A. (Ohio State Univ. Columbus, OH United States)
Hoffman, Richard, Jr. (Essential Research, Inc. Cleveland, OH United States)
Date Acquired
August 17, 2013
Publication Date
February 1, 1996
Publication Information
Publication: Space Photovoltaic Research and Technology 1995
Subject Category
Energy Production and Conversion
Funding Number(s)
CONTRACT_GRANT: NAG3-1461
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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IDRelationTitle19960045564Analytic PrimarySpace Photovoltaic Research and Technology 1995
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