We report the results of an investigation of the structural properties and relaxation of misfit stress with transmission electron microscopy and x-ray diffraction techniques. Epitaxial films of ZnSe were grown on GaAs by molecular-beam epitaxy of thicknesses ranging from 0.05 to 4.9 μm. The films contain stacking fault defects up to thicknesses of about 150 nm. Above 150 nm perfect misfit dislocations are generated from surface sources and the stacking fault defects to accommodate the lattice mismatch. The majority of dislocations observed are of the 60° type with Lomer edge type dislocations observed in a much lower concentration. The density of misfit dislocations increases with increasing epilayer thickness. Above about 1 μm the films exhibit biaxial tension which we believe is due to thermal expansion differences of ZnSe and GaAs. Good agreement is observed between microscopic and diffraction measurements of the relaxation phenomena.
Interdiffusions at Ge/GaAs heterojunctions formed by the epitaxial deposition of Ge films on GaAs have been studied for temperatures ranging from 650–800 °C. The diffusion coefficients of Ge in GaAs have been found to be 1.6×10−5 exp(−2.06/kT) for Cr: and Si:doped GaAs. After the diffusion heat treatment, Ge was found to be p type and ohmic.
Articles you may be interested inAtomic layer deposited beryllium oxide: Effective passivation layer for III-V metal/oxide/semiconductor devices J. Appl. Phys. 109, 064101 (2011); 10.1063/1.3553872Pulse response of thin III/V semiconductor photocathodes A simple procedure for the rapid formation of uniform native oxides on various III-V semiconductor materials is described. A puIsed applied potential drives an anodic oxide formation process on the semiconductor immersed in a glycol:water:acid solution. Uniform oxides up to 2000 A thick can be grown in a few minutes at room temperature and used to define areas for current injection into the semiconductor. AlGaAs diode lasers fabricated with 50-pm-wide current stripes defined by pulsed anodic oxide had threshold current densities substantially lower than lasers fabricated with 50-,um-wide stripes defined by chemical-vapor-deposited SiO,.
We report a detailed study of the effect of lattice mismatch on ZnSe epilayers grown on 〈001〉 GaAs by molecular beam epitaxy using photoluminescence (PL), x-ray diffraction, and transmission electron microscopy (TEM) techniques. We find that our samples are of high quality, exhibiting sharp and strong bound excitons, and that these bound excitons shift to higher energies due to tetragonal distortion as the thickness of the ZnSe epilayer is systematically reduced from ∼1 to 0.1 μm. Fairly good agreement is found between PL and x-ray data for the total strain relaxation as a function of layer thickness. TEM measurements are also used to estimate an inelastic component of the strain relaxation in the layers.
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