Some aspects of hydrogen plasma treatment of anti-modulation doped near surface GaAs/AIGaAs single quantum well structures/ Yu. A. Bumai, G. Gobsch, R. Goldhahn, N. Stein, A. Golombek, V. Nakov, T. S. Cheng

Abstract

The MBE grown anti-modulation doped GaAs/AIGaAs structures with near surface single quantum wells (QWs) were exposed to a DC hydrogen plasma (~400eV) and investigated using PL, PLE and PR spectroscopy at 5 K. Strong acceptor related free to bound transition (FB) dominates for QW related PL but excitonic features are still observed in PLE spectra. After hydrogen plasma treatment the PL intensity of FB transition from QW was strongly increased for above AIGaAs band gap excitation and was unchanged for below AIGaAs one. These results are consistent with atomic hydrogen passivation of deep defects in Al-GaAs barriers. At the same time radiative excitonic recombination was quenched by hydrogenation. PLE and PR spectra indicate on a strong increase of electric field in subsurface region of the structure after hydrogenation. The increase of electric field GaAs barriers. At the same time radiative excitonic recombination was quenched by hydrogenation. PLE and PR spectra indicate on a strong increase of electric field in subsurface region of the structure after hydrogenation. The increase of electric fieldin anti-modulation doped structure after hydrogen plasma treatment is supposed to be due to passivation by atomic hydrogen of surface states that leads to unpinning of Fermi level from mid gap to carbon acceptor level position in GaAs cap layer. It causes the further band bending and surface electric field increase that strongly suppress excitonic recombination in near surface QWs.