CRYSTAL GROWTH AND STUDIES OF SOME TERNARY SEMICONDUCTOR COMPOUNDS

Abstract

The TlGaSe2 single crystal was grown in the solid state laboratory at Aswan by very slow cooling from its melt by a technique, which is related to the Bridgman technique. The product ingot was identified with x-ray analysis. The obtained specimen was prepared with the desired dimensions for the electrical, optical absorption and for the photoconductivity measurements. The results obtained can be summarized as following:

(i) The temperature dependence of electrical conductivity for TlGaSe2 single crystal. The influence of temperature on the electrical conductivity was investigated in the temperature range from 77K to 300K for the TlGaSe2, which could be divided into three regions. This study was carried out in a temperature range, extending from 140K to 300K. The temperature range can be divided into three regions. The first region is from 140K to260K in which the conduction could be attributed to the electronic transition from the valence level to the acceptor level, where the sample was found to be p-type. The activation energy through this region was 1.23eV. Above 240K the conductivity falls and returns to increase with the temperature increasing. This behavior may be due to phase transition. The second region was from 260K to 280K in which the conductivity made abrupt change, which due to transition region. At high temperatures above 280K the intrinsic part starts. The activation energy estimated in this part equals 2.4eV which nearly corresponds to the published value [69]. The activation energy was calculated for the third region by means of the intrinsic behaviour of the semiconduction from the slope of the Log (cr)-1000/T curve in the high temperature region.