The size dependent properties of the Hall mobility and etch-pit dislocations in Ge hetero-epitaxial layers were investigated. Pure Ge thin films were grown by molecular beam epitaxy using pattern guided growth at 650C and compared with homo-epitaxially grown films. The results revealed enhanced Hall mobility and lower dislocation density as the pattern size decreased. The number of etch-pit dislocations was decreased by one order of magnitude and the Hall mobility measured with different sizes of van der Pauw patterns was enhanced by two times as the pattern size was decreased from 200 x 200μm2 to 3 x 3μm2. Raman spectroscopy was also employed to characterize residual strain and crystalline quality of the epitaxial films with respect to the pattern size. It was concluded that nano-scale pattern guided hetero-epitaxial growth of Ge may be a plausible method for monolithic integration of Ge optoelectronic or electronic devices onto a Si substrate.

Size Dependence of Hall Mobility and Dislocation Density in Ge Heteroepitaxial Layers Grown by MBE on a SiO2 Patterned Si Template. J.Lee, M.N.Chang, K.L.Wang: Microelectronics Journal, 2006, 37[12], 1523-7