Piezoelectric effect and the long-term resistance relaxations induced by uniaxial compression in p-GaAs/AlxGa1-xAs heterostructures

Long-term resistance relaxations induced by uniaxial compression in (001)p- GaAs/Al0.5Ga0.5As heterostructures are observed, and the main properties of these relaxations are investigated: the dependence of their character on t he direction of the uniaxial compression, the change in concentration of cu rrent carriers during the relaxation processes, and the quenching of the re laxations by temperature, illumination, and high electric fields. It is fou nd that the character of the relaxation process is different for compressio n directions [110] and [1(1) over bar0]: in the first case the concentratio n of two-dimensional holes in the quantum well decreases in the course of t he relaxation, while in the second case it increases. A model is proposed i n which the cause of the relaxations of the piezoresistance and the anisotr opic character of these relaxations is assumed to be the piezoelectric fiel d, the value of which, according to estimates, is \E-z\ = 1.152 x 10(4) V/c m per kbar. (C) 2000 MAIK "Nauka/Interperiodica".