On the Anisotropy of Scattering in Doped n‐Ge at Low Temperatures

Abstract

On Ge: Sb crystals with dopant concentrations, N , ranging between 8 x 10l6 and 1.5 x 10'' cm-3, the temperature and concentration dependences are found of the mobility anisotropy coefficient, K , over the temperature interval 4.2 K 5 T 5 180 K and at T 5 4.2 K. At temperatures T, close to the Hall-coefficient-maximum temperature, the K versus T curve exhibits a minimum at T = Tmin. The temperature Tmin corresponds to the boundary that separates the regions of weak and strong electron scattering. At sufficiently low temperatures, where the scattering is strong (the impurity and band states of electrons are mixed), neither the formulae for classical conductivity nor the formulae of the theory of quantum corrections permit a reliable determination of the value of mobility anisotropy K . Ha KpUCTaJIJIaX Ge

Model of DC Tunneling Conductivity via Hydrogen‐Like Impurities in Heavily Doped Compensated Semiconductors

“…in a cubic lattice of doping and compensating impurities. When deriving formula (7), it was taken into account that the average energy of Coulomb interaction of the selected impurity ion with ions in the nearest six sites of the impurity lattice is equal to zero:…”

“…Further, we consider the dopant concentration, the degree of its compensation ratio K, and also the temperatures T ( T j , for which, according to (7) and ( 8), the rms fluctuations W d ≫ k B T, W n ( W d and the concentration of c-band electrons nðTÞ ( Kð1 À KÞN d , where Kð1 À KÞ is the fraction of donor pairs that, according to the model, [41,42] limit the high-temperature region of hopping electron migration via them (see Figure 1, curve 2). Under these conditions, we have jE c ð Þ per j ( jE res j, and thus according to (4), the mobility edge is (see also Appendix A)…”

“…Near the insulator-metal transition, the temperature dependence of electrical resistivity (see Figure 1) has the form [5][6][7]…”

“…This fact (by the example of n ‐Ge:Sb) was noted in ref. [7], where it was shown that the electron impurity states near the Mott transition are quasi‐localized.…”

“…Near the insulator–metal transition, the temperature dependence of electrical resistivity (see Figure 1) has the form [ 5–7 ] where quantities and γ depend on the concentrations of majority and minority impurities; γ and are the parameters of the theory of quantum corrections to the electrical resistance; for ; .…”