Epitaxial growth of Si–Ge layers on Si substrates by plasma dissociation of SiH4 and GeH4 mixture

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Abstract
Silicon–germanium epitaxial layers were formed on (111) oriented Si substrates by the plasma dissociation of a mixture of SiH4 and GeH4. A growth rate of 33 Å/sec was obtained at a substrate temperature of 750 °C for Si–Ge epitaxial growth using 1×10−2 Torr of SiH4 and 1×10−4 Torr of GeH4 mixture as source materials. The introduction of GeH4 to SiH4 provided a good nucleation for epitaxy. Less than 1% of GeH4 is sufficient to reduce the concentration of the crystalline defects such as voids which form in the epitaxial layers at low substrate temperature with a high growth rate. The electron Hall mobility of layers coincided with that of bulk Si in the temperature range between 77 °K and room temperature.