PROPERTIES OF THE ALUMINUM-GALLIUM ARSENIDE IN THE PULSED ELECTRIC FIELD MODE

Abstract

In the development of modern semiconductor devices are increasingly used multicomponent semiconductors. One of the well-proven ternary compounds of the materials of the group is aluminum-gallium arsenide AlxGa1-xAs. For AlxGa1-xAs the transport properties in high electric fields have been investigated. One of the problems is the insufficient knowledge of the transport properties of charge carriers in a pulsed field mode.The purpose of the paper is to study the drift processes during the pulsed mode of the electric field in aluminum-gallium arsenide AlxGa1-xAs (at x = 0.225).The modeling was carried out on the basis of the relaxation equations for the conservation of momentum, energy and concentration. Using the two-valley ГL-model, calculations were performed for each valley and averaged taking into account their population. The most typical electron scattering mechanisms have been researched: impurity (at neutral atoms and impurity ions) and phonon (acoustic, optical, and inter-valley). The temperature dependence of the pulse scattering rates was analyzed, and the electron mobility was calculated. It is shown that the result of the mobility simulation is in а good agreement with the experiment. The effect of the "overshoot" of the drift velocity is investigated. For Al0.225Ga0.775As, a numerical experiment was conducted on the effect of the electric field pulse parameters on the drift velocity: amplitudes of the field strength, pulse duration, and front magnitude.It is shown that the pulse-like change of the field leads to a short "overshoot" of the drift velocity. Greater field amplitude corresponds to an increase in the maximum value of the drift velocity. However, this is accompanied by a reduction in the time for which the effect of the "overshoot" appears. The pulse duration of the electric field does not affect the peak value of the drift velocity. The increase of the pulse front duration leads to a significant decrease in the transport properties in strong electric fields. A comparison is made of the peak values of the drift velocity and the length of the “ballistic range” of the electron in aluminum-gallium arsenide Al0.225Ga0.775As and gallium arsenide GaAs.