Microscopic Measurements of Electrical Potential in Hydrogenated Nanocrystalline Silicon Solar Cells: Preprint

Research output: Contribution to conferencePaper

Abstract

We report on a direct measurement of electrical potential and field profiles across the n-i-p junction of hydrogenated nanocrystalline silicon (nc-Si:H) solar cells, using the nanometer-resolution potential imaging technique of scanning Kelvin probe force microscopy (SKPFM). It was observed that the electric field is nonuniform across the i layer. It is much higher in the p/i region than in themiddle and the n/i region, illustrating that the i layer is actually slightly n-type. A measurement on a nc-Si:H cell with a higher oxygen impurity concentration shows that the nonuniformity of the electric field is much more pronounced than in samples having a lower O impurity, indicating that O is an electron donor in nc-Si:H materials. This nonuniform distribution of electric field implies amixture of diffusion and drift of carrier transport in the nc-Si:H solar cells. The composition and structure of these nc-Si:H cells were further investigated by using secondary-ion mass spectrometry and Raman spectroscopy, respectively. The effects of impurity and structural properties on the electrical potential distribution and solar cell performance are discussed.
Original languageAmerican English
Number of pages8
StatePublished - 2012
Event2012 MRS Spring Meeting - San Francisco, California
Duration: 9 Apr 201213 Apr 2012

Conference

Conference2012 MRS Spring Meeting
CitySan Francisco, California
Period9/04/1213/04/12

NREL Publication Number

  • NREL/CP-5200-54833

Keywords

  • electrical potential
  • hydrogenated nanocrystalline silicon
  • NC-Si:H
  • PV
  • solar cells

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