GaAs on Si Grown by MBE: Progress and Applications for Selectivity Doped Heterojunction Transistors (SDHTs).

Recent progress of GaAs-on-Si technology is reviewed and the importance of initial nucleation is emphasized. Growth initiation with a Ga prelayer at a suitable low temperature combined with migration enhanced epitaxy and in-situ thermal annealing has a prospect of giving substantially improved material quality. During the initial growth, use of the minimum necessary As sub 4 Ga flux ratio is found to be critical. The random alignment of the major axis of the oval defects is suggested to be an alternative simple technique to detect the presence of antiphase domains. Patterned growth or post growth patterning releases tensile stress only if the growth edges are free. GaAs-on-Si was completely relaxed from stress by post-growth patterning to 5microns x 5microns size patterns. Steps on the surface due to substrate misorientation do not affect the two dimensional electron gas (2DEG) transport properties in AlGaAs/GaAs selectively doped heterojunction transistor (SDHT) structures. For a sheet density of 10 sup (12) cm sup (-2), the 2DEG mobility >50,000 cm sup 2 V sup (-1) s sup (-1) at 77 K was obtained on Si substrates, which is sufficient for fabrication of high performance SDHTs. The study shows that GaAs-on-Si has a great potential for SDHT technology.