Mobility enhancement by reduced remote impurity scattering in a pseudomorphic In0.7Ga0.3As/In0.52Al0.48As quantum well high electron mobility transistor structure with (411)A super-flat interfaces grown by molecular-beam epitaxy

Abstract

We have carried out a Shubnikov–de Haas (SdH) measurement at 4 K and investigated the electronic properties and scattering mechanisms in a pseudomorphic In0.7Ga0.3As/In0.52Al0.48As quantum well high electron mobility transistor (QW-HEMT) structure with a thin spacer thickness of 3 nm grown on a (411)A-oriented InP substrate by molecular-beam epitaxy (MBE). Electrons occupied the zeroth and first subbands in the 12-nm-thick In0.7Ga0.3As channel layer at two-dimensional electron gas (2DEG) densities of 3.10×1012 and 0.99×1012 cm−2, respectively. 2DEG mobilities of the (411)A sample for the zeroth and first subbands were μ0=52 000 and μ1=66 000 cm2/V s, which were much higher than those of the (100) QW-HEMT structure (μ0=22 000 and μ1=26 000 cm2/V s). The result indicates that the electron mobility of the (411)A sample is enhanced by reduction of remote impurity scattering because the spacer thickness (Lsp=3 nm) and distribution of sheet doped impurities are laterally uniform in the (411)A In0.7Ga0.3As/In0.52Al0.48As QW-HEMT structure.