Isotropic interface roughness of pseudomorphic In_0.74Ga_0.26As/In_0.52Al_0.48As quantum wells grown on (411)A InP substrates by molecular beam epitaxy

Abstract

Anisotropy of the interface roughness has been investigated for pseudomorphic In0.74Ga0.26As/In0.52Al0.48As modulation doped quantum wells (MD‐QWs) grown on (411)A and (100) InP substrates by molecular beam epitaxy. Significant difference of low‐temperature electron mobility between two different in‐plane current directions ([0$ \bar 1 $1] and [011]) was observed for the (100) MDQW with a well width of 4 nm, while it was not observed for the (411)A MD‐QW. The observed electron mobility was analyzed by the theory of interface roughness scattering. Lateral size of the roughness along the [0$ \bar 1 $1] 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). (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)