EPITAXY OF SI1-XGEX BY ULTRAHIGH-VACUUM CHEMICAL-VAPOR-DEPOSITION USING SI2H6 AND GEH4

Abstract

Disilane and germane were used to grow Si1-xGex epilayers at 550 degrees C by ultrahigh-vacuum chemical vapor deposition (UHVCVD). The solid composition x and growth rate of Si1-xGex were evaluated from double-crystal X-ray rocking curves and show very strong dependence on the total source gas flow rate ([GeH4]+[Si2H6]) and the gas ratio ([GeH4]/[GeH4]+[Si2H6]). The solid composition increases with increase of the gas ratio and also with increasing the total source flux by keeping gas ratio constant. The growth rate increases with the solid composition at lower values and then becomes saturated in the higher composition range (x>0.22). The results can be explained by the relationships of the source fluxes, relative incorporation efficiency at activated surface sites and hydrogen desorption under different growth conditions.