INFLUENCE OF INTERDIFFUSION PROCESSES ON OPTICAL AND STRUCTURAL-PROPERTIES OF PSEUDOMORPHIC IN0.35GA0.65AS GAAS MULTIPLE-QUANTUM-WELL STRUCTURES/

Interdiffusion has been investigated in molecular-beam epitaxially (MB E)-grown, highly strained In(0.35)Ga(0.06)5As/GaAs multiple quantum we ll (MQW) structures. Thermal intermixing and impurity-free interdiffus ion (IFID) was induced via rapid thermal annealing (RTA) at temperatur es between 700 and 950 degrees C using GaAs proximity caps and electro n-beam evaporated SiO2 cap layers, respectively. Both reduced photolum inescence (PL) linewidths and increased PL intensities were observed f ollowing interdiffusion-induced band-gap shifts ranging from 6 to 220 meV. PL microscopy (PLM) investigations were utilized to study the ons et of strain relaxation due to dislocation generation. Two types of li ne defects were found in the proximity-cap annealed samples, depending on the annealing temperature and the number of QWs: misfit dislocatio ns with the dislocation lines parallel to [110] directions and [100]-o riented line defects. No dislocations were observed in the SiO2-cap an nealed samples over the entire temperature range investigated here. Re sonant Raman scattering measurements of the 1LO/2LO phonon intensity r atio were used for a semiquantitative assessment of the total defect d ensities, including point defects (PDs). Whereas increasing PD densiti es and the formation of line defects were observed in the proximity-ca pped samples as the annealing temperature was increased, no deteriorat ion of the structural quality due to an increased PD density was obser ved in the case of the SiO2-cap annealed samples. (C) 1996 American In stitute of Physics.