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The Distribution of Occupied Deep Levels in a-Si:H Determined from CPM Spectra

Published online by Cambridge University Press:  21 February 2011

Nobuhiro Hata  and
Sigurd Wagner
Nobuhiro Hata
Affiliation:
Department of Electrical Engineering, Princeton University, Princeton, NJ 08544
Sigurd Wagner
Affiliation:
Department of Electrical Engineering, Princeton University, Princeton, NJ 08544
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Abstract

We report the determination of the distribution of occupied defect states in hydrogenated amorphous silicon from the deconvolution of constant photocurrent measurement (CPM) spectra, and the modelling of the distribution with the defect pool.

The CPM spectra were taken on undoped a-Si:H samples either in their as-grown state, in the annealed state, after quenching from high temperature, or after light-soaking. The spectra were deconvoluted to account for transitions from deep levels and from valence band tail states to a conduction band assumed to have a sharp edge. As-grown or annealed-state samples show a peak at 1.0 eV (0.2 eV FWHM) below the conduction band edge. Assuming a mobility gap of 1.9 eV, this peak lies 0.9 eV above the valence band edge. We ascribe this peak to the Do/+ transition. CPM spectra of light-soaked and thermally quenched samples show shifts in the peak position and increases in die peak height in accordance with the defect pool model. The model calculations agree with the CPM results, so that the applicability of CPM spectral analysis to obtaining detailed values of defect pool parameters is demonstrated.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 219: Symposium A – Amorphous Silicon Technology - 1991 , 1991 , 611
Copyright
Copyright © Materials Research Society 1991

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References

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