The effect of coupling barrier thickness on structural and optical properties in asymmetrically coupled GaN/Al0.5Ga0.5N/GaN multiquantum wells

Abstract

The structural and optical properties of coupled, multiquantum-well structures, consisting of GaN(10 Å)/Al0.5Ga0.5N(12 or22 Å)/GaN(20 Å) bounded by Al0.5Ga0.5N (100 Å) barriers, were investigated by high resolution x-ray diffraction, transmission electron microscopy, and photoluminescence measurements. We studied the carrier dynamics in asymmetric double quantum wells by analyzing the temperature-dependent and time-resolved photoluminescence spectra. Carrier tunneling between the coupled quantum wells affected the optical properties. In our analysis of the effect of the carrier tunneling in terms of free-carrier screening, the effect was much weaker for the sample with Tib=12 Å than for that with Tib=22 Å.