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Characterization of Gap Defect States in Hydrogenated Amorphous Silicon Materials

Published online by Cambridge University Press:  01 February 2011

Lihong Jiao  and
C. R. Wronski
Lihong Jiao
Affiliation:
[email protected], Grand Valley State University, School of Engineering, 301 W. Fulton St, Grand Rapids, MI, 49504, United States, (616)3316844
C. R. Wronski
Affiliation:
[email protected], Pennsylvania State University, Electrical Engineering, University Park, PA, 16802, United States
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Abstract

An enhanced simulation model based on the carrier recombination through these states was developed to characterize the gap defect states in hydrogenated amorphous silicon materials (a-Si:H). The energy dependent density of electron occupied gap states, kN(E), was derived directly from Dual Beam Photoconductivity (DBP) measurements at different bias currents. Through Gaussian de-convolution of kN(E), the energy peaks of the multiple defect states, including both neutral and charged states, were obtained. These energy levels, together with the information on the capture cross sections, were used as known input parameters to self-consistently fit the subgap absorption spectra, the electron mobility-lifetime products over a wide range of generation rates, as well as the energy dependent density of electron occupied gap state spectra. Accurate gap state information was obtained and the nature of the defect states was studied. Simulation results on light degraded hydrogen diluted, protocrystalline a-Si:H show that the density of charged states is 2.3 times that of neutral states. The two states close to the midgap act as effective recombination centers at low generation rates and play key roles in photoconductivity studies.

Keywords

amorphousSidefects
Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 1066: Symposium A – Amorphous and Polycrystalline Thin-Film Silicon Science and Technology—2008 , 2008 , 1066-A04-05
Copyright
Copyright © Materials Research Society 2008

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References

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