Identifying Electronic Properties Relevant to Improving Stability in a-Si:H-Based Cells and Overall Performance in a-Si,Ge:H-Based Cells

Research output: NRELSubcontract Report

Abstract

The work done during this second phase of the University of Oregon's NREL subcontract focused on degradation studies in both pure a- Si:H and a-Si,Ge:H alloys, as well as a detailed study of the interface between these two materials in a-Si:H/a-Si,Ge:H heterostructures. All samples discussed in this report were produced by the glow-discharge method and were obtained either in collaboration withUnited Solar Systems Corporation or with researchers at Lawrence Berkeley Laboratory. First, the results from our a-Si,Ge:H degradation studies support the conclusion that considerable quantities of charged defects exist in nominally intrinsic material. Researchers found that on light-soaking, all the observed defect sub-bands increased; however, their ratios varied significantly. Second,researchers performed voltage pulse stimulated capacitance transient measurements on a-Si:H/a-Si,Ge:H heterostructure samples and found a clear signature of trapped hole emission extending over long times. Finally, researchers began comparison studies of the electronic properties of a-Si:H grown by glow discharge either with 100% silane, or with silane diluted in H2 or He gas. The results onthese samples indicate that the films grown under high hydrogen dilution exhibit roughly a factor of 3 lower deep defect densities than those grown using pure silane.
Original languageAmerican English
Number of pages30
StatePublished - 1997

Bibliographical note

Work performed by University of Oregon, Eugene, Oregon

NREL Publication Number

  • NREL/SR-520-22701

Keywords

  • amorphous silicon
  • amorphous silicon-germanium
  • photocurrent
  • photovoltaics (PV)
  • transient photocapacitance (TPC)
  • transit capacitance spectroscopy

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