The hetero-epitaxial growth of GaAs on nominal (100) Ge/Si substrates was investigated. The root-mean-square surface roughness of the sample where the first few monolayers of the GaAs were nucleated by migration enhanced epitaxy (MEE) was 4 times smaller when compared to the sample without such a process, indicating a better surface planarity. From (004) X-ray diffraction rocking curve measurements, the full-width at half-maximum of the GaAs layer nucleated by MEE was 40% lower when compared to that of the GaAs layer without such a process, indicating better crystal quality. Furthermore, it was found that the sample where the GaAs layer was nucleated by MEE experienced early relaxation. As the MEE process promoted 2-dimensional growth, the GaAs layer where nucleation was initiated by such a process had fewer island-like formations. This led to a pseudomorphically grown GaAs layer, which experienced a higher strain when compared to the GaAs layer with more island-like formations, where most relaxation occurred on the free surface of the islands. Therefore, for the same layer thickness, the GaAs layer on (100) Ge/Si substrate where nucleation was initiated by MEE relaxed first.

Heteroepitaxial Growth of GaAs on (100) Ge/Si Using Migration Enhanced Epitaxy. H.Tanoto, S.F.Yoon, W.K.Loke, K.P.Chen, E.A.Fitzgerald, C.Dohrman, B.Narayanan: Journal of Applied Physics, 2008, 103[10], 104901