Heteroepitaxy and characterization of Ge‐rich SiGe alloys on GaAs

Growth of SiGe alloys on GaAs substrates at temperatures as low as 590 °C is described. The growth has been accomplished using the pyrolysis of disilane (Si2H6) and germane (GeH4) at such temperatures. The layers were characterized electrically and show n‐type conduction with carrier concentrations of ∼1×1018 cm−3. The high quality of the SiGe layers is evident in the Rutherford‐backscattering/channeling results on SiGe/GaAs structures. A χmin of 5.6% has been obtained for a Si0.05Ge0.95 layer on GaAs. χmin increases with increasing silicon content in the SiGe layers. The SiGe alloy layers were also studied by x‐ray diffraction, and the composition was determined assuming coherent, tetragonally distorted growth of SiGe on GaAs. The distortion calculations, based on theoretical elastic constants, were confirmed using Auger electron spectroscopy to determine alloy composition.