The electronic spectrum and electrical properties of germanium with a doubly charged gold impurity on both sides of the L 1 ⇄ Δ1 intervalley transition for uniform pressures of up to 7 GPa

Abstract

The dependences of resistivity ρ and the Hall coefficient R<0 on hydrostatic pressure P(P≤7 GPa) were studied at room temperature in Ge:(Au, Sb) with a partially populated (at 0 K) doubly charged Au level E Au 2− on both sides of the intervalley transition that occurred for P≅2.8 GPa. In terms of the two-band model, the baric dependences ρ(P) and R(P) and also the similar dependence of the Hall mobility with allowance made for interband scattering were calculated; the results agree satisfactorily with the experimental data. Characteristic parameters of the charge carriers and the baric coefficients for energy gaps between the edges of the L1 and Δ1 subbands in the conduction band and the E Au 2− level were determined. It was ascertained that the position of the energy level for a doubly charged gold impurity in germanium is fixed with respect to the valence-band top. The density-of-state effective mass of electrons in the (100) minimum of the conduction band of germanium was determined experimentally (and using the known values of the band parameters) and was found to be mdΔ=62/3(m∥m ⊥ 2 )1/3=1.05m0. It is shown that Ge:Au2− can be used to check the uniformity of pressure of up to 10 GPa.