Si crossdoping control and defect control in GaAs/Si heterojunctions grown by molecular-beam epitaxy

Abstract

The effects of growth procedure on the crystal defects and stresses of GaAs/Si polar/nonpolar heterojunctions grown by molecular‐beam epitaxy directly on 4° off (100) towards [110], and (211) misoriented Si substrates have been investigated by Raman scattering and Rutherford backscattering channeling. The FWHM of the Raman peak at room temperature and the ion channeling minimum yield Xmin is reduced with cooling rate decrease and with substrate (100) misorientation and (211) misorientation. The stress in (100) growths is about 109 dyn/cm, and in (100) off 4° [110] is 108 dyn/cm. A suitable termination procedure has been described. Si outdiffusion causes a crossdoping problem, and we have studied the effects of temperature on the interface crossdoping by Auger profiles and have found that crossdoping is strongly dependent on the growth temperature and the postgrowth heat treatment. Crossdoping of Si into the GaAs at the interface region can be controlled by using an AlGaAs/GaAs superlattice with an interrupted growth process and relatively low‐growth temperatures for AlGaAs/GaAs of 620 °C/570 °C. A multiple step growth procedure for successful growths of GaAs on Si has been developed and is described.