Short-term fatigue of photoluminescence in a-Si: H deposited at different temperatures

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Abstract
Strong fatigue of photoluminescence (PL) was observed under continuous excitation at 80 K in a-Si: H samples deposited at different substrate temperatures Ts. Within the first 3-minute stage of fatigue, the PL intensity reaches a nearly steady-state value at a level of 60% of the unfatigued intensity in films for which Ts = 70°C. Total recovery of PL intensity was found on annealing fatigued samples at room temperature. The time dependence of the PL intensity decay varies with the substrate temperature showing power-law behaviour in samples of high Ts and exponential behaviour in samples of Iow Ts The experimental results will be discussed within the framework of two non-radiative channels implying the breaking of weak bonds and the conversion of charged defect centres.