Contribution of resonant states to the conductivity of HgTe

Abstract

Measurements of the Hall effect and conductivity are performed on HgTe in the temperature range 4 to 40 K and magnetic field up t o 70 kG. The analysis of conductivity tensor versus magnetic field enables t o establish the influence of different types of carriers on the total conductivity. The concentration of the conduction band electrons versus temperature is determined from the low magnetic field experimental data. By comparing t)his dependence with the theoretical one the position and concentration of discrete acceptor levels are determined. It is found that the energy of the acceptor level decreases from 2.3 to 1.7 meV when the acceptor concentration increases from 2 x lo1* to 7 X 10l8 c m 3 . A significant contribution of the low-mobility electrons (p < 5 x lo3 cm'/Vs) to the conduction is established.Messungen des Halleffekts und der Leitfahigkeit werden an HgTe im Temperaturbereich 4 bis 40 K und magnetischen Feldern bis zu 70 kG durchgefuhrt. Die Analyse des Leitfahigkeitstensors als Funktion des Magnetfeldes ermoqlicht die Bestimnlung des Einflusses verschiedener Ladungstragersorten an der Gesamtleitfahigkeit. Die Konzentration der Leitungsbandelektronen iiber der Temperatur wird aus den experimentellen Werten bei niedrigem Magnetfeld bestimmt. Durch Vergleich dieser Abhangigkeit mit theoretischen Werten werden die Lage und Konzentration der diskreten Akzeptorniveaus bestimmt. Es wird gefunden, daS die Energie des Akzeptorniveaus von 2,3 auf 1,7 meV abnimmt, wenn die Akzeptorkonzentration von 2 x 1018 auf 7 x 1018 ansteigt.Ein betrachtlicher Beitrag von Elektronen mit niedriger Beweglichkeit ( p < 5 x lo3 cm2/Vs) zur Leitfahigkeit wird festgestellt.

Impurity Band Conduction in HgTe. II. Theoretical Analysis

“…Both concentrations of the same order of magnitude. Keeping in mind all assumptions and limitations used in [14] and in this paper it is clear that the parameters NF and NF are only roughly estimated.…”

“…I n this paper the impurity concentration has been estimated from (9). The impurity concentration estimated in [14], NF, and the impurity concentration estimated in this paper, NF, are shown in Table 1. Both concentrations of the same order of magnitude.…”

“…One can only obtain the activation energy Each. Activation energy obtained b y assuming an impurity band is equal to the energy of a discrete level E, obtained in [14]. If E, shown in Fig.…”

“…3, From the data presented in [14] i t is impossible to calculate independently the energy E, , and the halfwidth AE,. One can only obtain the activation energy Each.…”

Analysis of magnetic field dependent Hall data in narrow bandgap Hg1−xCdxTe grown by molecular beam epitaxy

“…[2][3][4][5][6][7][8][9] However, during the past decade it has been shown that such anomalous Hall characteristics can be explained by one of at least three different mechanisms not related to the energy spectrum ͑see review by Ivanov-Omskii et al 10 and references therein͒. The first possibility is the presence of microinhomogeneities in the HgCdTe crystal which may be of technological origin.…”