WIDTH OF EXCITON LINE IN THE LOW-TEMPERATURE PHOTOLUMINESCENCE OF INXGA1-XAS GAAS STRUCTURES WITH SINGLE QUANTUM-WELLS/

The low-temperature photoluminescence of an In0.13Ga0.87As/GaAs hetero structure with three single quantum wells has been studied. The wells had widths of 20, 37, and 63 angstrom. The structure was grown by mole cular beam epitaxy. The experimental results are compared with corresp onding data on other heterostructure systems. The emission from the we lls is two or three orders of magnitude more intense than the luminesc ence from the GaAs layers. The half-width of the exciton line from the 37-angstrom well is 1.4 meV. This figure is at the level of the best published data for wells with comparable dimensions. The half-width of the exciton luminescence line of In0.13Ga0.87As/GaAs structures is ca lculated as a function of the width of the quantum well for broadening mechanisms involving fluctuations of the composition and ''island'' f luctuations of the well width. Analysis of the experimental data leads to the conclusion that the quantum wells with widths of 37 and 63 ang strom are of high quality. The predominant mechanism for the broadenin g of the exciton line in these wells is the composition inhomogeneity of the solid solution, with a fluctuation length scale of 8-10 angstro m and a standard deviation sigma congruent-to 1 X 10(-3). Exciton peak s due to a recombination of excitons bound to neutral impurities have been observed.