Characterization of hydrogenated amorphous silicon using the constant photocurrent method

Date

1992-08

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Abstract

The objective of this wor~ is to study the electrical and f;.-("' -4 ,._ " :;- optical properties of hydrogenated amorphous silicon using the constant photocurrent method {CPM}. The absorption coefficients have been obtained for both undoped and phosphorus-doped a-Si: H films. The CPM spectrum has been compared with the absorption spectrum obtained from photothermal deflection spectroscopy. Some important parameters, such as the yrpac~ energy, optical gap, and defect density, have been obtained from the CPM spectrum. The light induced creation of defects has been investigated for different exposure times at 100 mWfcm2 illumination intensity. :li.-. -iJ . ~ '~ ' These light induced defects can be annealed out by heating the . - sample to above 150 - 200°C. The experimental data agree with the bond breaking model. According to this model, the weak Sisi bonds in the matrix are broken, or altered, followed by local atomic rearrangement into metastable equilibrium.

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Keywords

Amorphous semiconductors -- Defects -- Spectra, Silicon -- Defects -- Spectra, Absorption spectra

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