A GeSi-buffer structure for growth of high-quality GaAs epitaxial layers on a Si substrate

Abstract

A SiGe-buffer structure for growth of high-quality GaAs layers on a Si (100) substrate is proposed. For the growth of this SiGe-buffer structure. a 0.8-mum Si-0.1 Ge-0.9 layer was first grown. Because of the large mismatch between this layer and the Si substrate, many dislocations formed near the interface and in the low part of the Si0.1Ge0.9 layer. A 0.8-mum Si0.05Ge0.95 layer and a 1-mum top Ge layer were subsequently grown. The strained Si0.05Ge0.95/Si0.1Ge0.9 and Ge/Si0.05Ge0.95 interfaces formed can bend and terminate the upward-propagated dislocations very effectively. An in-situ annealing process is also performed for each individual layer. Finally, a 1-3-mum GaAs film was grown by metal-organic chemical vapor deposition (MOCVD) at 600degreesC. The experimental results show that the dislocation density in the top Ge and GaAs layers can be greatly reduced, and the surface was kept very smooth after growth, while the total thickness of the structure was only 5.1 mum (2.6-mum SiGe-buffer structure + 29.5-mum GaAs layer).