OPTICAL STUDIES OF HETEROINTERFACIAL GROWTH INTERRUPTS IN TYPE-II GAAS ALAS SUPERLATTICES BY TIME-RESOLVED PHOTOLUMINESCENCE IMAGING/

We have quantitatively characterized the heterointerfaces in type-II G aAs/AlAs short-period structures with various types of growth interrup ts. The quality of the heterointerfaces is governed by two factors: th e magnitude of the potential fluctuations or interface roughness and t he density of nonradiative defect centers incorporated at the heteroin terfaces during growth. We have quantified these aspects of the hetero interfaces through photoluminescence (PL), PL time-decay, and time-res olved PL-imaging measurements. We find that growth interrupts at the n ormal heterointerfaces significantly improves the quality of the inter faces over growth with no interrupts in regard to the interface roughn ess. Further, the transport of the excitons along the heterointerfaces may be explained by interface roughness induced scattering. We also f ind that growth interrupts at only the normal interfaces substantially reduces the nonradiative trap densities at the heterointerfaces. (C) 1995 American Vacuum Society.