KINETICS OF SI GROWTH ON GE(100) IN SI2H6 GAS-SOURCE MOLECULAR-BEAM EPITAXY AND LOW-PRESSURE CHEMICAL-VAPOR-DEPOSITION

The kinetics of Si heteroepitaxial growth on Ge(100) with Si2H6 was in vestigated. Intermittent Si2H6 exposure showed that at temperatures be low 450 degrees C, the thermal desorption of H-2 is much slower than r eactive sticking of Si2H6. With continuous Si2H6 exposure between 10(- 5) and 10(-2) Torr, the activation energy for growth was 41 kcal/mol. The growth rate was constant irrespective of pressure below (4-6) x 10 (-4) Torr (the pressures used in gas-source molecular beam epitaxy), w hereas at higher pressures (those of low-pressure chemical vapor depos ition (LPCVD)) depended on the square root of pressure. The growth kin etics in LPCVD can be explained by assuming a fast equilibrium between sticking of Si2H6 and recombinative desorption of silyl radicals dist ributed on the monohydride covered surface. The decomposition of the s ilyl radical, releasing H-2, is the possible rate-limiting step.