Time-resolved investigations of sidewall recombination and in-plane diffusivity in dry-etched InGaAs/GaAs air-post structures

Nonradiative carrier recombination in dry-etched InGaAs/GaAs air-post structures is investigated by time-resolved photoluminescence measurement. Both linearly and squarely size-dependent regions are observed in the measured carrier lifetime. It is shown that in-plane diffusivity D_r and sidewall nonradiative recombination velocity S_r can be simultaneously evaluated using a carrier diffusion model. Comparing an as-etched sample and a sample wet etched after dry etching shows that D_r as well as S _r are changed by removing the subsurface layer at the sidewall by wet etching. Possible causes of this change and the mechanism determining S _r are discussed.