High quality single-crystal germanium-on-insulator on bulk Si substrates based on multistep lateral over-growth with hydrogen annealing

Germanium-on-insulator (GOI) is desired for high performance metal-oxide-semiconductor transistors and monolithically integrated optoelectronics. We demonstrate a promising approach to achieve single-crystal defect-free GOI by using lateral over-growth through SiO₂ window. The dislocations due to the lattice mismatch are effectively terminated and reduced in SiO₂ trench by selective area heteroepitaxy combined with hydrogen annealing. Low defect density of 4× 10⁶ cm-2 and low surface roughness of 0.7 nm (root-mean-square) on GOI are confirmed by plan-view transmission electron microscopy and atomic force microscopy analysis. In addition, the excellent metal-semiconductor-metal diode electrical characteristics fabricated on this GOI confirm Ge crystal quality. The selectively grown GOI structure can provide the monolithic integration of SiGe based devices on a Si very large scale integration (VLSI) platform.