Misfit dislocations are often transported to the interface between crystals by glide. In materials with the diamond or sphalerite structures, glide is inhibited by the Peierls stress. The aim of this paper is to present a theory for misfit accommodation which includes the effect of the Peierls stress. It is used to explain the elastic strains present in films of germanium on gallium asrenide and to explain the reduction of these strains by a high-temperature anneal. The strains in germanium on gallium arsenide, and the effect of temperature upon them, are not explained by earlier theories for the accommodation of misfit between one crystal and another.

Ag—52 at.% Cu films were prepared by coevaporation onto 0.005 in. thick vitreous silica plates held at liquid-nitrogen temperature. The interference function I(K), where K=4π sinθ/λ, was evaluated from the elastic x-ray scattering of the film and compared with I(K) of the liquid alloy, measured at 1000°C, and with a model I(K) based on fcc microcrystals containing 125 atoms. The Fourier transforms of K[I(K)—1] yielded the reduced distribution functions G(r) =4πr[ρ(r)—ρ0]V(r), where ρ(r) is the weighted atomic density at a distance r from any reference atom, ρ0 is the average atomic density, and V(r) is the size factor of the diffracting domains. Both I(K) and G(r) indicate that the alloy film cannot be characterized as amorphous but is micropolycrystalline with fcc structure. The size of the microcrystals can be estimated from G(r), i.e., from the value of r beyond which G(r) is zero within the scatter of the experimental points. A value of less than 16 Å has thus been found. I(K) and G(r) of the liquid alloy are characteristic of the close-packed liquid metals with a distance of less than 15 Å beyond which no short-range order can be detected.

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The compatibility of Ge and normalGaAs , in terms of their temperature dependent mechanical properties, is described in this paper. Examination at room temperature of epitaxial Ge layers grown on wafers of single crystal, semi‐insulating normalGaAs , at substrate temperatures of 700°C by pyrolytic dissociation of GeH4 , reveals evidence of plastic deformation immediately following the epitaxial deposition process. Plastic deformation is observed in epitaxial Ge layers grown at 350°C, by disproportionation of GeI2 , only after a subsequent annealing cycle to at least 500°C. The low substrate temperature Ge films, however, show elastic bending of thin substrates after deposition and cooling to room temperature. Based on these observations, it is possible to estimate the differential thermal expansion coefficient between Ge and normalGaAs false(1×10−6/°Cfalse) , and to use this result to estimate the critical shear stress for plastic deformation under low strain rate conditions false(6.7×107 normaldynes/cm2false) . Interface dislocations are not observed.