PHYSICA B-CONDENSED MATTER, vol.348, pp.272-279, 2004 (SCI-Expanded)
Experimental and theoretical results on low electric field transport of two-dimensional electron gas (2DEG) in AlGaAs/GaAs high electron mobility transistor (HEMT) channel are reported at lattice temperature T-L = 1.7 K under zero magnetic field. The electron temperature (T-e) and the drift velocity (nu(d)) dependence on the electric field (F) and the electron density in the 2DEG channel are presented. In addition, the variation of the electron temperature with the drift velocity is obtained. The results are obtained for the electric field in the region of 0.01-100V/cm and in the electron temperature range of 1.7-60 K. It is shown that the electron temperature of 2DEG is a non-monotonous function of the electric field. The results also indicate that electron heating is seen to occur for the electric field F > 0.1 V/cm which corresponds to the electron temperature T-e = 2 K. A sharp increase in the electron temperature T-e and in the drift velocity nu(d) with the electric field below electron temperature of 40 K is seen. The variation of electron temperature with drift velocity is very slow in the same electron temperature range where acoustic phonon emission due to deformation potential is the dominant energy loss mechanism of electronic system. When F > 5 V/cm and T-e > 40 K, where the optic phonon emission is a dominant relaxation mechanism, the electron temperature changes linearly with electric field and the drift velocity increases very rapidly with electron temperature. Also, the drift velocity starts to saturate in this regime. The experimental results are compared with theoretical results and a good agreement is obtained at the electron temperatures of T-e < 50K. Above the electron temperature of 50K, a disagreement is observed between the experimental and the theoretical results which indicates that additional scattering mechanisms should be taken into account and the accuracy of the assumptions concerning the electrons and phonons made in the theory should be questioned. (C) 2003 Elsevier B.V. All rights reserved.