The electron–electron interaction in gapless semiconductors

Abstract

The effect of the Coulomb interaction on the dielectric function, the mobility, and the energy spectrum of gapless semiconductors is analyzed. It IS shown that the hole energy is strongly renormalized due to the nonlocality of the potential. The resulting shape of the valence band and its dependence on the electron concentration is considered. The nonlocality of the lattice potential diminishes the ground state energy of the acceptor.

Specific features of the temperature dependence of the conduction electron concentration in the narrow-gap and zero-gap states of Cd x Hg1 − x Te

“…Therefore, it is necessary to recall the main cases encountered in practice. It was shown in [1,3] that the concentration, at which the Fermi level energy coincides with the acceptor level energy (ε F = ε 0 ), is determined as (5) Then (6) The temperature dependences of n/N 0 for a zero gap semiconductor of the Cd x Hg 1 -x Te type calculated in [1,3] for m p /m n = 18 are presented in [1,3,7,8]. It follows from these data that the dependence n(T) has an unusual shape (since N 0 for each sample is con stant) and is determined by the concentration of acceptor impurities N a and donor impurities N d (Fig.…”

“…Therefore, all donor states in them should be ionized starting at the lowest temperatures. It was shown in [1,3] that, depending on the concentration of donor and acceptor impurities, several cases are imple mented in zero gap semiconductors. In most of them, the carrier concentration n(T) should pass through a minimum approximately in the temperature range T = 15-20 K. These specific features should have an affect on other electron properties.…”

“…The theory of impurity states for zero gap Cd x Hg 1 -x Te type semiconductors was considered in [1][2][3][4][5]. The main idea of the theory amounts to the fact that donor levels are absent in zero gap semiconductors with the ratio of effective masses of electrons and holes m p ӷ m n , while quasi discrete acceptor levels with the energy ε 0 are present in the continuous spectrum of the conduc tion band.…”

Specific Features of Kinetic Effects Measured in (Cd, Hg) Te in Quantizing Magnetic Fields

“…1 and 2. Mobility calculations made with the common Brooks-Herring formula, neglecting the compensation, but allowing for a: contribution of disorder scattering [6] and for an increase in dielectric constant E in ZG samples [7], lead us to the conclusion that in the measured samples the acceptor concentration" NA is much less than the donor one N,. It can be seen from Table 1 that the calculated and measured mobility values for samples 1 and 2 are very close to each other.…”

The electronic energy spectrum of zero-gap semiconductors

“…Задача об уровнях акцептора при произвольном отношении масс решалась во многих работах, например, с помощью вариационного метода 70 Подробное исследование зависимости волновой функции от расстоя-ния до примесного центра показывает, что сначала она экспоненциально спадает с характерным масштабом порядка боровского радиуса тяжелой дырки a h = H 2 E 0 /m h e z , затем этот экспоненциальный спад переходит в степенной, волновая функция спадает как 1/г 3 и, наконец, при г ^> a h степенной спад сменяется экспоненциальным, но характерным масштабом спада является уже среднегеометрическая величина %/]fmiE 0 где а г = е о й 2 /т г е 2 -боровской радиус легкой дырки. При решении задачи о положении уровня основного состояния наличие далекого экспонен-циального хвоста несущественно, и его можно не учитывать при вариа-ционных расчетах.…”