Comparison of ammonia plasma and AIN passivation by plasma-enhanced atomic layer deposition

摘要

Surface passivation of GaAs by ammonia plasma and A1N fabricated by plasma-enhanced atomic layer deposition are compared. It is shown that the deposition temperature can be reduced to 150 ℃ and effective passivation is still achieved. Samples passivated by A1N fabricated at 150 ℃ show four times higher photoluminescence intensity and longer time-resolved photoluminescence lifetime than ammonia plasma passivated samples. The passivation effect is shown to last for months. The dependence of charge carrier lifetime and integrated photoluminescence intensity on A1N layer thickness is studied using an exponential model to describe the tunneling probability from the near-surface quantum well to the GaAs surface.