Effect of valley-spin degeneracy on the screening of charged-impurity centers in two- and three-dimensional electronic devices

Abstract

Accurate characterization of charged impurity centers is of importance for the electronic devices and materials. The role of valley-spin degeneracy on the screening of an attractive ion by the mobile carriers is assessed within a range of systems from spin-polarized single-valley to six-valley. The screening is treated using the self-consistent local-field correction of Singwi and co-workers known as STLS. The bound electron wave function is formulated in the form of an integral equation. Friedel oscillations are seen to be influential especially in two-dimensions which cannot be adequately accounted for by the hydrogenic variational approaches. Our results show appreciable differences at certain densities with respect to simplified techniques, resulting mainly in the enhancement of the impurity binding energies. The calculated Mott constants are provided where available. The main conclusion of the paper is the substantial dependence of the charged impurity binding energy on the valley-spin degeneracy in the presence of screening. 73.20.Hb, 71.45.Gm

Diffusion Monte Carlo study of a valley-degenerate electron gas and application to quantum dots

“…17. The method was later applied to charge impurities by Bulutay et al 18 The calculations of Ref. 15 were performed for Յ 6, too few flavors to gauge the applicability of the analytic many-flavor approximation, which is estimated to apply at around six or more flavors.…”

“…[17]. The method was later applied to charge impurities by Bulutay et al [18]. The calculations of Ref.…”

Charged Bose condensate screening of hydrogenic impurities in two and three dimensions

“…The reduction of the binding energy of a hydrogenic impurity due to electron screening was studied extensively in the past [1][2][3][4][5][6][7][8][9]. Such calculations are important for impure metals and doped semiconductors.…”

“…The binding energy was calculated by using different approximations for the screening function. The effect of screening by an electron gas on a single charged impurity in three dimensions (3D) [1][2][3][4][5][6] and in two dimensions (2D) [5][6][7][8][9] was considered. In 3D it was found that the binding energy of a positively charged impurity vanishes if the screening density of electrons is larger than a critical density, the Mott density.…”

Many-Body Effects for Bound States in the Quasi-One-Dimensional Electron Gas: Effects of the Valley Degeneracy

“…The effects of the valley degeneracy on the bound-state energy of screened impurities has recently been discussed for the two-and three-dimensional electron gas using the test-charge±test-charge interaction [12]. A detailed discussion of the differences between the test-charge±test-charge interaction potential and the test-charge±electron interaction potential was given before [6,7,9].…”