Nonohmic Conductance and Mechanisms of Energy Relaxation in 2D Electron Gas in GaAs∕InGaAs∕GaAs Heterostructures

Abstract

The effects of heating 2D electron gas in GaAs/InGaAs/GaAs structures at temperatures of 0.4–4 K and electron densities of (1.5–6) × 1015 m−2 are studied. For the entire range of temperatures and densities studied, the rate of energy relaxation agrees well with theoretical predictions of the energy relaxation via electron scattering at the piezoelectric and deformation potential of acoustic phonons. It is shown that the widely used analytical expressions for energy relaxation rate, which were obtained in low-and high-temperature limits, are applicable only when the relations between the Fermi quasi-momentum and the momentum of thermal phonons are strictly observed. It is shown that the dependence of the energy relaxation rate on the electron density is a nonmonotonic function. For example, at the lattice temperature of 1.4 K, it initially increases as the electron density decreases to n = 2.5 × 1015 m−2, but then starts to decrease as the density decreases further.