The surface energy of various planes in Si, GaAs, and GaP was measured by the use of a modified spark discharge method, previously used successfully in metals. Surface energy values were determined for the following cleavage planes in these crystals: Si {111}∼1.14 J/m2, Si {110}∼1.9 J/m2, GaAs {110}∼0.86 J/m2, and GaP {110}∼1.9 J/m2. The Si surface energy value was compared with previous experimental measurements. The Si {110}, GaAs {110}, and GaP {110} values were compared only to theoretical estimations, since as far as it is known, the surface energy of these planes have never been measured experimentally. Berg-Barrett x-ray topography and chemical etch pit analysis verified that plastic relaxation did not occur under the test conditions used. The cleavage surface energies determined in this work were in good agreement with previous theoretical estimations. Experimental observations confirmed a lack of plastic energy dissipation and a stability of cleavage propagation which indicated that the measured surface energies were close to the intrinsic values.

The development of a preferred crystallographic orientation in the plane of growth, an in-plane texture, is addressed in a model that incorporates anisotropic growth rates of a material and self-shadowing. Most crystalline materials exhibit fast growth along certain crystallographic directions and slow growth along others. This crystallographic growth anisotropy, which may be due to differences in surface free energy and surface diffusion, leads to the evolution of specific grain shapes in a material. In addition, self-shadowing due to an obliquely incident deposition flux leads to a variation in in-plane grain growth rates, where the ''fast'' growth direction is normal to the plane defined by the substrate normal and the incident flux direction. This geometric growth anisotropy leads to the formation of elongated grains in the plane of growth. Neither growth anisotropy alone can explain the development of an in-plane texture during polycrystalline thin-film growth. However, whenever both are present ͑i.e., oblique incidence deposition of anisotropic materials͒, an in-plane texture will develop. Grains that have ''fast'' crystallographic growth directions aligned with the ''fast'' geometric growth direction overgrow grains that do not exhibit this alignment. Furthermore, the rate of texturing increases with the degree of each anisotropy. This model was used to simulate in-plane texturing during thin-film deposition. The simulation results are in excellent quantitative agreement with recent experimental results concerning the development of in-plane texture in sputter deposited Mo films.

The microstructure and texture of thin MO films sputtered onto the native oxide of Si(100) wafers were investigated with both conventional reflection x-ray pole figures, and transmission electron microscopy and diffraction. Films were grown at two deposition rates (powers), 34 nm/min (1.5 kW) and 67 mn/min (3.9 kW), onto both moving and stationary substrates, under otherwise identical experimental conditions. The microstructure of the MO films evolved into a zone 2 microstructure within the first 2 pm of growth. The development of both out-of-plane and in-plane textures was found to be influenced by deposition rate and geometry. Films grown at the lower deposition rate exhibited predominantly (110) textures, while films grown at the higher rate exhibited predominantly (110) textures up to a film thickness of-0.5 ,um and (111) textures above a film thickness of-1 ,YAIL Films with the (110) textures developed grains with elongated footprints and faceted surfaces, while films with the (111) textures developed grains with elongated triangular footprints and faceted surfaces. In all of the films deposited onto moving substrates, an alignment of the grains normal to the tangent plane (defined by the substrate normal and the direction of platen rotation) was observed. In all of the films deposited onto stationary substrates, the development of an in-plane texture was suppressed. These results suggest that a combination of geometric, energetic, and kinetic mechanisms are contributing to the evolution of the microstructure and texture in the MO films.-4610

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