Using hydrostatic pressure for evaluating the effect of a fluctuating potential on the energy spectrum of charge carriers in crystalline semiconductors

Abstract

As known [1, 2], doped compensated semiconductors (in which the concentration of free charge carriers is small compared to the concentration of ionized impurities) exhibit smooth, large-scale fluctuations of random potential with certain characteristic amplitudes ( γ ). The role of this chaotic potential increases with decreasing temperature, while at a fixed temperature it grows under the action of pressure as the free carrier concentration decreases [3]. It is important to develop a method for evaluating the effect of the chaotic potential on the energy spectrum of charge carriers and to assess the correctness of relations obtained for defect-free crystals so as to provide a quantitative analysis of experimental data in each particular case. It should be noted that the pressure coefficients of the energy gaps in semiconductors are virtually pressure-independent at not very high pressures. Moreover, the pressure-induced changes of the deepest minima e Γ , e L , and e X in the conduction bands of various semiconductors (IV, II‐VI, III‐V, IV‐VI, and II–IV–V 2 ) are also approximately the same [4‐8]. Previously, the pressure coefficients of the e Γ , e L , and e X extrema relative to the values in absolute vacuum were determined [5] based on a concept according to which the energy of deep strongly localized states in some semiconductors is independent of the uniform (hydrostatic) pressure.