The effect of photodegradation on electroluminescence in a-Si:H devices

Abstract

The electroluminescence spectra and the carrier recombination lifetime distribution in a-Si:H devices have been measured in thin p-i-n, p-b-i-n and thick p-i-n devices in the annealed (A) and degraded (B) states. At room temperature and thin samples the effect of photo-degradation is a slightly reduction in the main band (1.2 eV) luminescence intensity along with a slight shift to lower energy in the defect band (0.8–0.9 eV) intensity; while in 2–10 μm samples a more pronounced reduction of the 1.2 eV band is found. At low temperatures, where the 1.2 eV luminescence dominates, no degradation effect on the spectrum's line shape is found for all samples that have been measured. It is suggested that the 0.8 eV luminescence is dominated by defects near the interfaces while the 1.2 eV luminescence is a bulk effect.