LOW-TEMPERATURE HETEROEPITAXY OF GE ON SI BY GEH4 GAS LOW-PRESSURE CHEMICAL VAPOR-DEPOSITION

The crystalline quality of Ge grown epitaxially on Si can be improved by using GeH4/H-2 gas low-pressure chemical vapor deposition at a low temperature of 410-degrees-C and surface-cleaning processing with a purified-H-2 flow prior to GeH4 introduction into a CVD reactor. H-2 flow processing is carried out at growth temperature. The dislocation density of a 1.3-mu-m thick Ge film is nearly 2 x 10(8) cm-2, which is as low as that of molecular-beam epitaxy (MBE)-grown Ge films. Stacking faults commonly generated in the CVD-grown Ge films at temperatures higher than 700-degrees-C are not observed. The 700-degrees-C heat treatment of the Ge film reduces dislocation density to 2 x 10(7) cm-2 and causes no interface reaction between Ge and Si. This technique is superior to conventional chemical vapor deposition (CVD) techniques for Ge epitaxial growth.