Growth And Characterization Of Gallium Arsenide On Silicon On Sapphire And Silicon

A study has been conducted to investigate and compare the growth, strain, defects, electrical and optical properties of GaAs layers grown simultaneously on silicon-on-sapphire (SOS) and Si substrates using a two-step metalorganic chemical vapor deposition (MOCVD) growth procedure. A variety of techniques have been used to characterize and investigate the different properties of these two layers. Among them, x-ray diffraction was used to determine the lattice dimensions and thereby the sign of residual strain, x-ray rocking procedures to measure the strain and crystallinity, and variable temperature x-ray diffraction to investigate the temperature dependence of residual strain. Scanning electron microscopy (SEM) was used to examine the surface morphology. Transmission electron microscopy (TEM) was used to observe the microstructure and defect distribution as well as defect density. Also secondary ion mass spectroscopy (SIMS) was used to study the cross-diffusion from substrates. In addition, capacitance-voltage (C-V) measurements and Hall-effect measurements were used to determine the carrier concentration and mobility. Finally, photoluminescence (PL) was used to observe the low-temperature optical response of GaAs layers. The results of these investigations of GaAs on SOS and Si substrates are compared as a function of the thickness of GaAs layers. Finally, the effects of residual strain, presence of defects and cross-diffusion of Si on electrical and optical properties of GaAs layers are discussed.