Abstract

Based on its spectral characteristics, cw photoluminescence (PL) has been used mostly to determine the quality of multiple quantum wells (MQWs); no laser-intensity dependence of PL has been used to diagnose recombination processes in MQWs. Here, we report our first observation of cw PL saturation in multiple narrow asymmetric coupled QWs (ACQWs) at room temperature. We show that characterization of such phenomena can be a simple and effective technique for diagnostics of the recombination processes of the multiple narrow QWs. The sample had 25 undoped ACQW individual pairs, each of them consisting of two GaAs QWs (1.8 nm and 3.2 nm), coupled by 1.5-nm Al_0.4Ga_0.6As barrier (see Fig. 1). A 10-nm barrier was used to isolate the adjacent ACQWs from each other. The PL spectra were measured at different pump laser intensities in the cw regime, as shown in Fig. 2. At low laser intensity, a pronounced peak near λ-775.4 nm with a broad shoulder near λ~758.9 nm can be identified as the heavy-hole and light- hole transition peaks (see Fig. 2).

© 1992 Optical Society of America