Sub-bandgap optical absorption and light-induced defects in amorphous silicon

Abstract

Photothermal deflection spectroscopy (PDS) and the constant photocurrent method (CPM) are used to monitor the changes in density of deep defects associated with the Staebler‐Wronski effect. These values are correlated with the electron spin resonance (ESR) signal, dc photoconductivity, and minority‐carrier μτ values determined from bias‐dependent carrier collection efficiency studies. The density of deep defects determined by subgap absorption grows with light‐soaking time t following the same functional form (t1/3) as the ESR signal. The initial and light‐induced defects have similar carrier recombination cross‐sections.