Atomic-Scale Characterization of Hydrogenated Amorphous-Silicon Films and Devices: Annual Subcontract Report, 15 April 1994 - 14 March 1998

Research output: NRELSubcontract Report

Abstract

The research is concerned with improving the electronic properties of hydrogenated amorphous silicon (a-Si:H) films and of photovoltaic (PV) cells that use these films. Two approaches toward this goal are being taken. One is to establish the character of silicon particle growth in the rf glow discharges that are used to make the films and PV cells, and to understand the particle incorporationinto the films. The ultimate goal of this effort is to find mitigation techniques that minimize the particle incorporation. During this contract period, we developed a novel particle light-scattering technique that provides a detailed and sensitive diagnostic of small (8-60-nm diameter) particles suspended in the discharge. We used this to measure the particle growth rates and densities, versusconditions in pure-silane discharges. The second program is directed toward measuring the electronic properties of thin-film PV cells, as a function of depth within the cell. The approach being taken is to use a scanning tunneling microscope (STM) to measure the depth-dependent electronic properties of cross-sectioned PV cells. During the present period, measurements on single and tandemamorphous silicon cells have been carried out. Using STM current-voltage spectroscopy, these measurements distinguish the boundaries between the highly conducting and intrinsic layers, and should allow one to deduce the chemical potential versus depth in the cell.
Original languageAmerican English
Number of pages26
StatePublished - 1998

Bibliographical note

Work performed by National Institute of Standards and Technology, Boulder, Colorado

NREL Publication Number

  • NREL/SR-520-24760

Keywords

  • a-SiH films
  • atomic-scale characterization
  • films and devices
  • hydrogenated amorphous silicon (a-Si:H)
  • photovoltaic
  • scanning tunneling microscopy (STM)

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