The effects of rapid thermal processing, upon material with various thicknesses of SiO2 encapsulant, were studied by using capacitance-voltage, secondary ion mass spectroscopic, and X-ray photo-electron spectroscopic methods. The processing was carried out at 760 or 910C, for a period of 9s. The results indicated that a decrease in carrier concentration was related to Ga out-diffusion through the SiO2. The decrease in carrier concentration was attributed to the formation of VGa-SiGa complex defects (self-activated centers). At 760C, the amount of Ga out-diffusion was larger in samples with a thick SiO2 coating. At 910C, the amount of Ga out-diffusion was larger in samples with a thin SiO2 coating. This behavior was explained by assuming the operation of 2 different types of driving force. These were interfacial thermal stresses, and an interfacial reaction between GaAs and SiO2. It was noted that interfacial thermal stresses enhanced Ga out-diffusion at 760C, whereas interfacial reactions enhanced such out-diffusion at 910C.

Ga Out-Diffusion in Rapid Thermal Processed GaAs with SiO2 Encapsulants. M.Katayama, Y.Tokuda, Y.Inoue, A.Usami, T.Wada: Journal of Applied Physics, 1991, 69[6], 3541-6

Table 5

 Diffusivity of Ga Self-Interstitials in GaAs