Single-particle relaxation times in a pseudomorphic In0.7Ga0.3 As/In0.52Al0.48As QW-HEMT structure with (4 1 1) A super-flat interfaces grown by MBE

Single-particle relaxation times in In0.7Ga0.3As/In0.52Al0.48As quantum well high electron mobility transistor (QW-HEMT) structures for two subbands (i=0 and 1) are studied by fast Fourier transform analysis of Shubnikoov-de Haas (SdH) oscillations measured at View the MathML source in order to investigate remote impurity (RI) scattering in the QW-HEMT structure with effectively atomically flat interfaces over a wafer-size area ((4 1 1)A super-flat interfaces) grown on a (4 1 1)A InP substrate by molecular beam epitaxy. The (4 1 1)A QW-HEMT structure with thin spacer thickness of View the MathML source shows two times longer single-particle relaxation times View the MathML source and View the MathML source) compared to those View the MathML source and View the MathML source) for the corresponding QW-HEMT structure with conventional (1 0 0) interfaces, indicating that RI scattering is much reduced in the (4 1 1)A sample. Calculations of τs(0) limited by RI scattering assuming random distribution of sheet-doped impurities show that the enhancement of τs(0) for the (4 1 1)A QW-HEMT structure cannot be explained by laterally uniform spacer thickness resulting from the (4 1 1)A super-flat interfaces. Much reduced RI scattering in the (4 1 1)A QW-HEMT structure is considered to be mainly caused by extremely uniform distribution of sheet-doped impurities.