Time-resolved photoluminescence of erbium centers in amorphous hydrogenated silicon

A time-resolved photoluminescence (PL) technique is employed to study the mechanisms of excitation and de-excitation of Er3+ ions in amorphous hydrogenated silicon (a-Si:H) at temperatures 5–300 K. The PL at 1.5 μm is found to arise within times shorter than a 100 ns after irradiation with a nanosecond laser pulse, indicating a fast energy transfer from the electronic excitation of a-Si:H to the Er3+ ions. The PL transients exhibit a stretched exponential decay with mean lifetime ranging from 20 to 35 μs when the temperature decreases from 300 K down to 5 K. The experimental results support the model of defect-related excitation and de-excitation of the Er3+ ions.