Subband effective mass and mobility of twohyphen;dimensional electrons in uniformly Sihyphen;doped Ga0.47In0.53As/Al0.48In0.52As multiple quantum wells

摘要

Subband effective mass and mobility of a twohyphen;dimensional electron gas inuniformlySihyphen;doped Ga0.47In0.53As/Al0.48In0.52As multiple quantum wells are estimated. In three samples with well widths of 130, 200, and 300 Aring; and a fixed barrier width of 68 Aring;, up to three twohyphen;dimensional subbands are found. Maximum enhancement of electron effective mass is 25percnt; over the bulk value at a Fermi energy of 108 meV. These estimated effective masses are slightly smaller than previously reported values, and this is explained by recent theories which assume only nonparabolic correction. When the temperature ratio, (Dingle temperature)/(mobility temperature), is assumed to be identical in different subbands in each sample, the electron mobility of the first excited subband is at most twice that of the ground subband in the sample with the widest well. The effects of intersubband scattering and of screening on the subband mobilities are also discussed.