Influence of interdiffusion processes on optical and structural properties of pseudomorphic In0.35Ga0.65As/GaAs multiple quantum well structures

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Abstract
Interdiffusion has been investigated in molecular‐beam epitaxially (MBE)‐grown, highly strained In0.35Ga0.65As/GaAs multiple quantum well (MQW) structures. Thermal intermixing and impurity‐free interdiffusion (IFID) was induced via rapid thermal annealing (RTA) at temperatures between 700 and 950 °C using GaAs proximity caps and electron‐beam evaporated SiO2 cap layers, respectively. Both reduced photoluminescence (PL) linewidths and increased PL intensities were observed following interdiffusion‐induced band‐gap shifts ranging from 6 to 220 meV. PL microscopy (PLM) investigations were utilized to study the onset of strain relaxation due to dislocation generation. Two types of line defects were found in the proximity‐cap annealed samples, depending on the annealing temperature and the number of QWs: misfit dislocations with the dislocation lines parallel to 〈110〉 directions and 〈100〉‐oriented line defects. No dislocations were observed in the SiO2‐cap annealed samples over the entire temperature range investigated here. Resonant Raman scattering measurements of the 1LO/2LO phonon intensity ratio were used for a semiquantitative assessment of the total...