Effects of Si(100) tilting angle and prelayer conditions on GaAs/Si heterostructures

Vicinal Si(100) substrates with tilting angles of 0–9° toward [01-1] have been investigated for the molecular beam epitaxy of GaAs-on-Si heterostructures. The major difference between tilting angles was found to be the GaAs(100) orientation which can be achieved on each angle; for the 7.5° it was too difficult and for 9.0° it was impossible to obtain GaAs[011] parallel (instead of perpendicular) to the Si [01-1] tilting direction, while this was reproducibly attainable for the 1.5–6.0° range, using pre-exposure of Si to As at 400°C. Smooth GaAs surfaces for angles above 1.5° can only be obtained for this GaAs orientation and thus the useful angle range is limited between 1.5–6.0°. Furthermore, material and device characterization results promote the choice of the 4.5° tilting angle from the above range slightly.