Heterointerface stability in GaAs-on-Si grown by metalorganic chemical vapor deposition

Abstract

The stability of the electrical and structural properties of GaAs directly deposited on Si by metalorganic chemical vapor deposition is examined. Extended annealing at 900 °C leads to substantial diffusion of Si across the heterointerface while under the same conditions there is no significant motion of Si incorporated as a dopant into the GaAs surface region. The degree of enhancement of Si diffusion ranges from a factor of ∼250 for 0.5-μm-thick GaAs films to ∼5 for 4-μm-thick films. The annealing time and GaAs layer thickness dependence of Si diffusivity near the interface is consistent with a defect-modulated mechanism. A large fraction of this mobile Si is electrically inactive.