I. G. Savel'ev

Energy relaxation of 2D electrons at an AlGaAs/GaAs heterojunction at helium temperatures

Abstract The peculiarities of 2D electron gas heating are derived from the comparison of temperature and field dependences of galvanomagnetic effects for one or two occupied size-quantized subbands. The main energy relaxaton mechanism at helium temperatures is shown to be the scattering by piezoelectric potential of acoustic phonons. Experimental data and theory show that while the carrier density increases, the temperature dependence of energy loss rate changes due to contribution of electrons in second subband to the energy relaxation processes.

Quantum transport effects in a two-dimensional electron gas as a tool for the investigation of heterointerfaces

We have studied the influence of interface defects on low temperature galvanomagnetic effects in a two-dimensional electron gas (2DEG). Experiments have shown a non-ideal character of the InP/In 0.53 Ga 0.47 As interface in modulation-doped structures with 2DEG grown by liquid phase epitaxy. That is why such structures have been chosen for investigation. The following galvanomagnetic effects were investigated at liquid helium temperatures: the Hall mobility; the oscillatory magnetoresistance in a magnetic field perpendicular to the heterointerface; the negative magnetoresistance in a weak magnetic field parallel to 2DEG. The quantitative analysis of these effects allowed one to determine the interface parameters: the amplitude δ=7-10 A and the lateral size Λ=50-70 A of small-scale interface fluctuation, the interface charge density N z =(8±2) ×10 19 cm -2 and the amplitude of large-scale 2DEG density fluctuations δn s /n s 5%

The Nonlinear Effects in 2DEG Conductivity Investigation by an Acoustic Method

The parameters of two-dimensional electron gas (2DEG) in a GaAs/AlGaAs het-erostructure were determined by an acoustical (contactless) method in the delocalized electrons region (B ≤2.5T). Nonlinear effects in Surface Acoustic Wave (SAW) absorption by 2DEG are determined by the electron heating in the electric field of SAW, which may be described in terms of electron temperature T e. The energy relaxation time τ ǫ is determined by the scattering at piezoelectric potential of acoustic phonons with strong screening. At different SAW frequencies the heating depends on the relationship between ωτ ǫ and 1 and is determined either by the instantaneously changing wave field (ωτ ǫ < 1), or by the average wave power (ωτ ǫ > 1).