DETERMINATION OF THE MICROSCOPIC QUALITY OF INGAAS-INALAS INTERFACES BY PHOTOLUMINESCENCE - ROLE OF INTERRUPTED MOLECULAR-BEAM EPITAXIAL-GROWTH

Photoluminescence (PL) studies have been carried out on 120 A InGaAs/InAlAs single quantum well structures grown by molecular beam epitaxy. Three types of samples were grown with the growth being interrupted before interface formation. The interruption times were 0, 2, and 3 min. The corresponding linewidth of the main excitonic transition associated with the quantum well was found to be 20, 16, and 10 meV, respectively, while the PL intensity changed by the ratio 1:0. 4:0. 1. We believe this behavior is due to a steady improvement in the interface quality due to interruption accompanied by impurity accumulation during the interruption. Analysis of the 10 meV linewidth, which is among the smallest ever reported, suggests that the InAlAs/InGaAs interface can be described by two-dimensional InAlAs and InGaAs islands which have a height of two monolayers and a lateral extent of about 100 A.