Surface structure of Ge(100) studied by He diffraction

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Abstract
The surface structure of Ge(100) has been studied by use of the technique of He diffraction. At room temperature the surface shows an apparent sharp (2×1) periodicity with additional contributions extending through the quarter-order beam positions of the c(4×2). For surface temperatures T≤150 K, the surface nearly completely orders into a c(4×2) with a residual contribution from an apparent (2×2) component. We compare the experimental results to eikonal scattering calculations based on surface potentials generated using a modified charge-superposition scheme. We find that the alternating tilted dimer model is most consistent with the experimental diffraction spectra, specifically for a dimer tilt angle of 6°±2°. The sensitivity of He diffraction to the Ge(100) surface structure is discussed.