Physica B 393 (2007) 285–291 Transport properties of Cd 0.8 Zn 0.2 Te crystals G.A. Gamal, M. Abou Zied, A.A. Ebnalwaled Ã Physics Department, Faculty of Science, South Valley University, Qena 83523, Egypt Received 1 July 2006; received in revised form 11 January 2007; accepted 23 January 2007 Abstract After Cd 0.8 Zn 0.2 Te (CZT) crystals were prepared by a special design based on Bridgman technique, the transport properties were investigated. The dependence of electrical conductivity, Hall effect, Hall mobility, charge carriers concentration and thermoelectric power on temperatures was carried out in the temperature range (228–500 K). The relaxation time for both majority and minority carriers was estimated. The scattering mechanism for carrier transport was discussed in the same temperature range. r 2007 Elsevier B.V. All rights reserved. PACS: 81.10.Fq; 81.10.h; 72.80.Ey; 05.60.Cd Keywords: Crystal growth; Semiconductors; Transport properties; Scattering mechanism; CdZnTe 1. Introduction Although the potential of CdZnTe for producing relatively large-volume gamma-ray spectrometers has been well demonstrated [1], numerous problems remain asso- ciated with growth process [2–6]. Crystal growth of CdZnTe is performed mainly by high-pressure vertical Bridgman (HPVB) and low-pressure horizontal or vertical Bridgman (LPB) method [7–13]. Undoped CdZnTe crystal is regarded as one of the most promising materials for room temperature nuclear detector [14]. Several reports have been made [15,16] to elucidate the nature of the defects, which have decisive role for the carrier lifetime. However, the dominant scattering mechanism for carrier transport and/or the value of the mobility for CdZnTe system still have some open questions. Very high mobilities of 1350 cm 2 V 1 s 1 (electron) and 120 cm 2 V 1 s 1 (hole) for Cd 0.8 Zn 0.2 Te at room temperature were reported [17]. These values are higher than those for Cd 0.9 Zn 0.1 Te [14] (electron 1000–1100 cm 2 V 1 s 1 , hole 50 cm 2 V 1 s 1 ). Further, the values are even much higher than those reported for chlorine-doped CdTe [18]. Since, up to our knowledge, many parameters are not known for CZT crystals, like transport parameters and their temperature’s dependence, we undertook such work to report the growth of Cd 0.8 Zn 0.2 Te crystals and the results of temperature dependence of the electrical con- ductivity, Hall mobility, thermoelectric power and the charge carrier’s density for Cd 0.8 Zn 0.2 Te crystals. 2. Experimental details The feed materials were synthesized with 6N-source material of Cd, Zn and Te. The chemicals were obtained from Aldrich. The percentage of the charge elements are 39% Cd, 5.7% Zn and 55.3% Te, the total mass of the components are (5.85 g Cd, 0.855 g Zn and 8.295 g Te). Small Cd excess was attached to this percentage, to grow crystals under Cd-annealing according to the previous recommendation [19]. The chemicals were introduced in the ampoule, which was then evacuated to 10 6 Torr and sealed under this vacuum. The growth experiment took place in a modiﬁed vertical Bridgman technique {traveling solvent method (TSM)}(see Fig. 1). The present technique introduces a suitable solution to the presence of the pulleys and hence their problems. In this apparatus the ampoule, with its charge, was supported in its holder where the holes were placed in a three-zone tube furnace. This technique ARTICLE IN PRESS www.elsevier.com/locate/physb 0921-4526/$ - see front matter r 2007 Elsevier B.V. All rights reserved. doi:10.1016/j.physb.2007.01.016 Ã Corresponding author. Tel.: +2 0 10 4034633. E-mail address: Kh_bnalwaled@yahoo.com (A.A. Ebnalwaled).