The Mobility of Electrons and Holes in HgTe in the Temperature Range of Intrinsic Conduction

Abstract

HgTe samples containing no acceptors are studied. The results of the investigation of Hall coefficient and conductivity versus magnetic field up to 20 kG in the temperature range 4 up t o 100 K are presented. Concentration and mobility of electrons and holes in the intrinsic range of the conductivity are calculated. Density state effective mass of holes mh = 0.3m0 is determined. It is shown that acoustic and optical phonon scattering are most important modes limiting the hole mobility.HgTe-Proben ohne Akzeptordotierung werden untersucht. Die Ergebnisse der Nessungen des Hallkoeffizienten und der Leitfiihigkeit werden als Funktion der magnetischen Feldstiirke bis zu 20 kG und im Temperaturbereich 4 bis 100 K vorgestellt. Konzentrationen und Beweglichkeiten von Elektronen und Lochern im Eigenleitungsgebiet werden berechnet. Die effektive Nasse der Locher wird zu mh = 0,3 m,, bestimmt. E s wird gezeigt, daB die akustische und optische Phononenstreuung der Hauptmechanismus ist, der die Locherbeweglichkeit begrenzt. IntroductionMercury telluride is a semiconductor with an inverted band structure [ l , 21. Recent papers concerning the physical properties of HgTe present consistent information about conduction band parameters [3 to 13, 251 and electron scattering mechanisms [14 to 191. The parameters of the valence band and the properties of holes in HgTe were investigated occasionally and rather scarce information is available.A problem which attained a wide interest is that concerning the impurity levels in HgTe [20 to 231. Electrical and optical properties of this semimetal depend sensitively on the presence of the resonant acceptor states. They manifest themselves as an additional density of states in the magnetooptical experiments [21, 221, and in the temperature dependence of the electron concentration [23, 271. They act also as the scattering centres seen in the temperature dependence of the electron mobility [l6]. The anomalous magnetic field dependence of the Hall coefficient and the Conductivity at low temperatures explained as a contribution of low-mobility electrons is correlated with the presence of the acceptor states [26, 271. These acceptor states were observed in all reported in the literature investigations of HgTe samples, even in those of very high purity. The contribution of low-mobility electrons to the conductivity makes the full analysis of the transport properties very difficult. I n this paper we show that samples containing no acceptor states are free of the low-mobility electrons as well. For these HgTe samples a full analysis of the transport properties was performed.

n- and p-Type HgTe Quantum Dot Films

“…However, this work shows that the mobility of electrons and holes are similar in the CQDs films. This is in contrast from bulk HgTe where the ratio of electron to hole mobility is about 100 at temperatures above 100 K . The similar electron and hole mobility in CQD films may be explained by the fact that transport is limited by the transmission through the barrier between the dots rather than by scattering inside the dots.…”

On the Anomalies in the Temperature Dependence of Conductivity in Hg1−xCdxTe

“…in the range of magnetic fields where crzz = const ( H < 5 kOe for specimen 2, H < 1 kOe for specimens 3, 4) 15. K, the behaviour of R ( H ) for our specimens obeys relation (2) with the coefficient a > 1, which corresponds to the situation when two sorts of electrons participate in the conductivity.…”

Nonelastic charge carrier scattering in mercury telluride

“…It can be explained in the following way. Experimental values of the hole mobility presented in [2,5,6] were obtained by taking the hole contribution to conductivity tensor components from experimental data (measurement accuracy of ∼10%) which for concentrations of p < 5 × 10 15 cm −3 results in lower values of several percent. However, in our opinion, this method of obtaining the experimental data of holes mobility is not quite correct.…”

“…Charge carrier scattering mechanisms and the mobility in HgTe have been rather well investigated over a wide temperature range [1][2][3][4][5][6][7][8][9]. These investigations were based on the relaxation time approximation which can be used for elastic scattering mechanisms.…”