NEW LOW-PRESSURE CHEMICAL-VAPOR-DEPOSITION TECHNIQUE FOR GE CRYSTALLINE THIN-FILMS

A new type of low pressure chemical vapor deposition for Ge thin films was investigated by using a gaseous mixture of GeF4 and Si2H6. At rel atively low gas flow ratios of Si2H6/GeF4, etching of Si substrates wa s observed and the film growth replaced the etching with an increase i n the gas flow ratio. The epitaxial growth was achieved at the low tem perature of 350-400-degrees-C on a Si(100) substrate, and at a higher temperature region polycrystalline growth took place. The experimental results suggested a major contribution of reductive surface reaction of GeF4 activated by Si2H6 to the Ge film growth.