GA0.25IN0.75AS INP QUANTUM-WELLS WITH EXTREMELY HIGH AND ANISOTROPIC 2-DIMENSIONAL ELECTRON-GAS MOBILITIES/

Measurements of modulation-doped Ga0.25In0.75As/InP quantum wells show , in the [-110] direction, a record electron mobility of 520 000 cm(2) /V s at 300 mK. A mobility difference of 15% between the [110] directi on and the [-110] direction is observed. This anisotropy is tentativel y attributed to an ordering effect. The mobilities at room temperature and at 77 K were 16 100 and 170 000 cm(2)/V s, respectively. By separ ating out the ionized impurity scattering from other scattering proces ses in the quantum well, we conclude that at low electron concentratio ns ionized impurity scattering is limiting the mobility, while alloy s cattering has a strong influence on the mobility at high electron conc entrations, From this result we determine the first experimental value of the alloy-scattering potential as Delta V=0.3 eV. (C) 1996 America n Institute of Physics.