Kinetics of Light-induced Metastable Defect Creation and Annealing in a-Si:H

Authors: ALP OSMAN KODOLBAŞ, AYNUR ERAY, ÖZCAN ÖKTÜ

Abstract: Constant Photocurrent Method (CPM) and steady state photoconductivity measurements are used to investigate the creation of light-induced metastable defects in a-Si:H at room temperature and their annealing. Light-induced metastable defect concentration N$_{d}$ varies with exposure time t_{e}as t_{e}^{r} with r=0.34\ pm 0.02, as expected from the recombination induced weak bond breaking model [1]. The validity of a stretched exponential model is also studied [2]. From the annealing experiments, the distribution of thermal annealing activation energies is calculated following the method proposed by Hata and Wagner [3]. Defects created at room temperature show a narrow distribution of annealing activation energies peaking at 0.97eV. The relation between photoconductivity and N_{d} is strongly nonlinear. Defects created at earlier times of illumination degrade photoconductivity more strongly, and these defects anneal out more easily than those created at later times of illumination.

Keywords: a-Si:H, Staebler-Wronski effect, Light induced metastable defect, CPM, Photoconductivity, Distribution of annealing activation energies.

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