Characterization of morphology and defects in silicon-germanium virtual substrates

Silicon-germanium heterostructures incorporating virtual substrates are suc cessfully used for both microelectronic and optoelectronic applications. Ho wever, their use is limited by their surface morphology (e.g. roughness) an d defect (e.g. threading dislocations) density. High quality silicon-german ium heterostructures incorporating virtual substrates have been grown epita xially using different methods. This study reports the effects of the growt h parameters on the morphology and defects in different silicon-germanium h eterostructures incorporating virtual substrates grown in the Southampton U niversity Microelectronics center (SUMC) by low pressure chemical vapor dep osition (LPCVD). Two types of structures: one with a linear and the other w ith a step variation of the germanium concentration in the virtual substrat e, were grown and characterized. Results obtained were in good agreement wi th others already reported in the literature for similar structures grown u sing different epitaxial techniques. (C) 2000 Kluwer Academic Publishers.