Growth of high quality Ge∕Si1−xGex on nano-scale patterned Si structures

Abstract

Heteroepitaxial growth of thick (∼6μm) Ge∕3μm SixGe1−x layers on nano-scale patterned Si substrates has been investigated. These nm scale structures are fabricated using interferometric lithography with reactive ion and wet-chemical etching techniques. The quality of the growth on the nanopatterned substrates was compared to growth on planar substrates. The quality of the epitaxial layers was characterized using scanning electron microscopy, transmission electron microscopy, high-resolution x-ray diffraction and etch pit density measurements. We demonstrated the nanopatterned structures produce significantly superior quality heteroepitaxial epilayers in comparison with unpatterned Si surfaces. The dislocation density of Ge epilayers on the nanopatterned Si was ∼ three orders magnitude lower than on planar Si. Growth on nanopatterned surfaces also reduced surface roughness and eliminated crosshatch patterns characterstic of planar surfaces.