Isotropic interface roughness of pseudomorphic In_(0.74)Ga_(0.26)As/ In_(0.52)Al_(0.48)As quantum wells grown on (411)A InP substrates by molecular beam epitaxy

摘要

Anisotropy of the interface roughness has been investigated for pseudomorphic In_(0.47)Ga_(0.26)As/In_(0.52)Al_(0.48)As modulation doped quantum wells (MD-QWs) grown on (411)A and (100) InP substrates by molecular beam epitaxy. Significant difference of low-temperature electron mobilitybetween two different in-plane current directions ([011] and [011]) was observed for the (100) MD-QW with a well width of 4nm. while it was not observed for the(411)A MD-QW.rnThe observed electron mobility was analyzed by the theory of interface roughness scattering. Lateral size of the roughness along the [011] direction (Λ = 5.8 nm) is 29% larger than that of the [011] direction (Λ = 4.5 nm) for the (100) interface. On the other hand, the (411 )A interface shows isotropic roughness (Λ ～ 4.5 nm) with much smaller amplitude (Δ = 0.24 nm) comparing to the (100) interface (Δ = 0.33 nm).