Photoluminescence spectroscopy was used to study GaAs/Al0.3Ga0.7As multiple quantum wells, grown at about 350C by means of molecular beam epitaxy. Under As-rich conditions, differing As pressures were used during the growth of various samples. It was found that the full-width at half-maximum of the photoluminescence peaks improved, at first, with decreasing As pressure. However, it then degraded due to the appearance of a shallow-level related emission peak when the As pressure was further decreased. In the

case of annealed samples, changes in their photoluminescence features revealed that the Ga vacancy, VGa, in the low-temperature samples could be precisely controlled via the As pressure used during growth. However, the influence of the As pressure upon As antisites, AsGa, became significant only when the As pressure was above 3.0 x 10-7Torr. A strong dependence of the photoluminescence features upon the As pressure was attributed to the differing control effect of the As pressure for VGa and AsGa. Following optimization of the As pressure, samples with a sharp photoluminescence peak and a high resistivity were obtained. The full-width at half-maximum of the photoluminescence peak was 0.0031eV, and could be compared with that of normal-temperature grown samples having the same structure. The results agreed well with a growth dynamics and compensation mechanism between shallow levels and deep levels.

Effects of As Pressure on Optical Features of Low-Temperature Grown GaAs/AlGaAs Multiple Quantum Wells. Y.J.Han, L.W.Guo, C.L.Bao, Q.Huang, J.M.Zhou: Journal of Crystal Growth, 2002, 236[1-3], 90-4