Growth and Dielectric Properties of DVT Grown GeS0.25Se0.75 Single Crystals

The present paper reports the growth of GeS0.25Se0.75 single crystals by direct vapor transport technique (DVT) using two zone horizontal furnace. The precise adjustment of the temperature gradient between source and growth zone of a horizontal furnace that enhance the transport of material in vapor form could result in the growth of gray, shining thin flakes of GeS0.25Se0.75 single crystals. The average dimensions of grown crystals were 0.90 x 0.56 cm2. As grown GeS0.25Se0.75 single crystals were used for dielectric measurement. The dielectric measurements were carried out by standard two electrode method using HP4284A LCR meter and a digital temperature controller DT4284. The entire measurement cycle was programmed by LABVIEW software. The dielectric properties i.e. capacitance (C) alternating current conductivity (σac) and dielectric constant (ε’) are measured in the frequency range 100 Hz to 1 MHz with different temperature from room temperature to 523 K, in the step of 50 K temperature using 4284A LCR meter. In this investigation, dielectric constant is observed to be high at lower frequency and it systematically decreases with increasing frequency up to 600 kHz and then after it nearly becomes frequency independent while dielectric loss tanδ decreases with temperature and frequency.