Samples of GaAs, which were encapsulated with thin films of amorphous Si at 450C, were annealed at temperatures of up to 1050C. The resultant poly-Si/GaAs interfaces were investigated by using secondary ion mass spectroscopy, Rutherford back-scattering spectrometry, and transmission electron microscopy. Little or no interdiffusion was detected at undoped Si/GaAs interfaces, whereas Si diffused into the GaAs (from P-doped or As-doped Si) to depths as great as 550nm after only 10s of annealing at 1050C. The flux of Si into GaAs was related to the fluxes of Ga and As into Si. Both fluxes increased with increasing dopant concentration in the Si. An enhanced diffusivity of Si into GaAs was attributed to the diffusion of point defects which were created by the diffusion of As and Ga into the encapsulant. It was deduced that the Si diffusivities in GaAs at doped polycrystalline Si interfaces were enhanced by factors of about 10000.

The Interdiffusion of Si, P, and In at Polysilicon/GaAs Interfaces. K.L.Kavanagh, C.W.Magee, J.Sheets, J.W.Meyer: Journal of Applied Physics, 1988, 64[4], 1845-54