Electron Energy Relaxation via Acoustic Phonon Emission in GaAs/Ga1?xAlxAs Multiple Quantum Wells: Effects of Base Lattice Temperature

Abstract

The two-dimensional (2D) electron energy relaxation associated with acoustic phonon emission in GaAs/Ga1—xAlxAs multiple quantum wells (MQW) has been investigated using hot-electron Shubnikov-de Haas (SdH) effect measurements performed at three different base lattice temperatures TL0 ≅ 1.7, 3.5 and 5.9 K. The modulation-doped MQW samples studied have quantum well widths LZ = 51, 75 and 78 Å, and only the lowest subband in each sample is populated with a 2D electron density of about 1.10 × 1016 m—2. The electron temperature (Te) has been determined from the lattice-temperature and electric-field dependencies of the amplitude of the SdH oscillations. The energy-loss rates show a power-law dependence on Te with an exponent γ, which depends on TL0. The experimental results are compared with the current theoretical models for power loss in 2D and 3D semiconductors, which include both piezoelectric and deformation-potential scattering. The electron-temperature dependence of power loss, determined experimentally at liquid-helium temperatures with TL0 ≅ 1.7 K, fits well to both the 2D and 3D theoretical models in the low-temperature regime, while the results at TL0 ≅ 3.5 and 5.9 K fit best to those in the intermediate-temperature regime. The results provide useful information about the relative magnitude of the deformation-potential and piezoelectric contributions to power loss.