Published online by Cambridge University Press: 17 March 2011
We describe novel 2-D structures that facilitate strain relief and allow us to obtain Ge epilayers that are free of defects. These structures can potentially absorb thermal expansion and lattice expansion mismatch as well as enable liftoff of heteroepitaxial layers for subsequent wafer reuse. Conventional lithography techniques were combined with reactive ion and wet-chemical etching to fabricate 2-D patterns of silicon posts. The dimensions of the posts were varied keeping the pitch (center to center distance) constant. Heteroepitaxial growth of Ge/SixGe1−x on these micrometer-scale structures was investigated. While, keeping the growth parameters constant, the geometry of the structures was varied to determine the optimum configuration for the highest quality heteroepitaxial growth. The quality of the Si1−xGex buffer system was investigated using high-resolution x-ray diffraction. Transmission electron microscopy (TEM) was used to analyze the epilayer cross-sections. Surface morphology was analyzed using scanning electron microscopy (SEM), atomic force microscopy (AFM) and optical microscopy. Our results show that the quality of the heteroepitaxial layers improves as the width of the posts in the 2-D pattern was decreased.