Photoluminescence observation of quantum confined stark effect caused by band bending near the surface of etched structures with GaAs/AlGaAs wells

Abstract
The interaction of electronic and excitonic states confined in quantum wells (QW) with nearby sulphur-passivated surface was studied by photoluminescence (PL). The redshift (up to 12 meV for 50A QW) and quenching (down to 10^-4 ) of QW PL line were observed with approaching of the surface closely to QW by wet etching. The predominant role of quantum-confined Stark effect (QCSE) caused by the near-surface band bending was revealed by the following observations: (1) long-range surface influence (>300A), (2) increasing of the redshift for the thicker QW's, (3) the redshift dependence on the excitation level. On the basis of QCSE theory all the parameters of depleted layer on excitation level are determined. The revealed model can be used for the explanation of the optical properties of etched nanostructures.