The transport properties of InP and GaAs epitaxial layers which had been grown onto exactly (001)-oriented Si substrates were investigated by means of temperature-dependent Van der Pauw measurements and anodic stripping. The electron concentrations at 300K decreased from about 1018/cm3, at the hetero-interface, to a constant level of 1016/cm3 towards the surface. These agreed well with the concentration profiles of Si donors. Their activation energy was equal to 0.0029 and 0.0013eV in InP/Si and GaAs/Si, respectively. At low temperatures, a marked decrease in the electron mobility at the hetero-interface occurred. Quantitative analysis led to a model in which charged dislocations were scattering centers. From a comparison of the dislocation densities of 2 x 108 and 108/cm2 in the vicinity of the surface of 2- and 3-thick layers, found by wet chemical etching, the occupation probability of the charged centers along the dislocation lines was deduced to be equal to 0.2 and 1.0 for InP and GaAs, respectively. At 300K, the electron mobility was almost unaffected by dislocation scattering, and values of 3600 (InP) and 3800cm2/Vs (GaAs) for electron concentrations of 2 x 1016 and 8 x 1016/cm3 were obtained. These values were close to those which were found for homo-epitaxial layers.

A.Bartels, E.Peiner, A.Schlachetzki: Journal of Applied Physics, 1995, 78[10], 6141-6