Effect of the growth parameters on the luminescence properties of high-quality GaAs/AlGaAs multiquantum wells on (1 1 1)A substrates by metal organic vapor phase epitaxy

Abstract

We report on a study of the growth parameters and their effect on the structural and optical properties of GaAs/AlGaAs multiquantum well (MQW) structures grown on novel (1 1 1)A-oriented GaAs substrates by atmospheric-pressure metalorganic vapor-phase epitaxy. The MQW structures have 25 periods with well widths ranging from 25 to 45 Å and an Al fraction in the barriers of around 25% and were grown at 600°C using V/III ratios ranging from 52 to 261 and various growth rates on exact and misoriented (1 1 1)A substrates. High-resolution X-ray diffractometry was used to assess the crystal quality and obtain structural information. The growth rates for GaAs on (1 1 1)A and (1 0 0) oriented substrates are compared. The optical quality was evaluated by low-temperature photoluminescence (PL) spectroscopy. We determined the optimum growth conditions to obtain high structural quality and PL emission intensity. A PL line width of 10.5 meV was achieved, which is the lowest value reported to date for GaAs/AlGaAs MQWs on (1 1 1)A or (1 1 1)B GaAs by any growth technique, corresponding to less than a ±1 monolayer fluctuation of the well width over the 25 periods.