CHARACTERIZATION AND DETERMINATION OF THE BAND-GAP DISCONTINUITY OF THE INXGA1-XAS/GAAS PSEUDOMORPHIC QUANTUM-WELL

Single and multiple quantum well samples have been grown by atmospheric pressure metalorganic chemical vapor deposition at In compositions from 9 to 28% and layer thicknesses ranging from 15 to 140 angstrom, depending upon the composition. Selected samples containing three quantum wells of a given composition but with different thicknesses were characterized by x-ray double-crystal diffractometry, low-temperature photoluminescence, and transmission electron microscopy (TEM). Using a simulation technique based on the dynamical theory of x-ray diffraction in concert with TEM measurements, the In composition in the quantum well as well as the thicknesses can be directly extracted. The peak positions of the photoluminescence are used to determine the strained and unstrained energy gap and the conduction band offsets associated with In(x)Ga1-x(As) of a given composition. We have found the discontinuities to be 60% of the difference in the energy gap of GaAs and strained In(x)Ga1-x(As).