Hot electron energy relaxation via acoustic phonon emission in modulation-doped In0.53Ga0.47As/In0.52Al0.48As heterojunctions with double-subband occupancy - art. no. 085301

The energy relaxation associated with acoustic phonon emission in lattice-m atched In0.53Ga0.47As/In0.52Al0.48As heterojunctions, has been investigated using Shubnikov-de Hass (SdH) effect measurements performed in the tempera ture range from 3.3 to 25 K, and at electric fields up to 200 Vm(-1). The t hickness (t(s)) of the undoped spacer layer in modulation-doped samples was in the range between 0 and 400 Angstrom. The SdH oscillations show that tw o subbands are populated for all samples except those with t(S)=400 Angstro m. The electron temperature (T-e) of hot electrons in each subband has been obtained from the lattice temperature (T-l) and applied electric field dep endencies of the amplitude of SdH oscillations. For the samples with t(S) = 0, 100, and 200 A, the power loss from the electrons in the first and seco nd subbands is found to be proportional to (T-e(3)-T-L(3)) for electron tem peratures in the range 3.3< T-e< 12 K, indicating that piezoelectric scatte ring is the dominant scattering mechanism. For the samples with t(S)=400 <A ngstrom>, however, in which only the first subband is populated, the power loss is approximately proportional to (T-e-T-L) in the same range of electr on temperatures. The experimental results are also compared with a three-di mensional model for electron energy loss by piezoelectric and deformation-p otential scattering.