Electrical and mechanical properties of vapour grown gallium monotelluride crystals

Abstract

The physical vapour deposition (PVD) of gallium monotelluride (GaTe) in different crystalline habits was established in the growth ampoule, strongly depending on the temperature gradient. Proper control on the temperatures of source and growth zones in an indigenously fabricated dual zone furnace could yield the crystals in the form of whiskers and spherulites. Optical and electron microscopic images were examined to predict the growth mechanism of morphologies. The structural parameters of the grown spherulites were determined by X-ray powder diffraction (XRD). The stoichiometric composition of these crystals was confirmed using energy dispersive analysis by X-rays (EDAX). The type and nature of electrical conductivity were identified by the conventional hot probe and two probe methods, respectively. The mechanical parameters, such as Vickers microhardness, work hardening index, and yield strength, were deduced from microindentation measurements. The results show that the vapour grown p-GaTe crystals exhibit novel physical properties, which make them suitable for device applications.

Keywords

gallium monotelluride / spherulites / whiskers / physical vapour deposition / electrical conductivity / microhardness

References

[1] Conway AM, Reinhardt CE, Nikolic RJ, Nelson AJ, Wang TF, Wu KJ, Payne SA, Mertiri A, Pabst G, Roy R, Mandal KC, Bhattacharya P, Cui Y, Groza M, Burger A. Exploration of GaTe for gamma detection. IEEE Nuclear Science Symposium Conference Record, 2007 1151

[2] Milne WI, Anderson JC. Threshold switching in gallium telluride single crystals. J. Phys. D, 1973, 6(17): 2115.

[3] Manfredotti C, Murri R, Rizzo A, Vasanelli L, Micocci G. Electrical properties of GaTe grown by various methods. Phys. Status Solidi A, 1975, 29(2): 475.

[4] Kunjomana AG, Chandrasekharan KA. Microhardness studies of GaTe whiskers. Cryst. Res. Technol., 2005, 40(8): 782.

[5] Reshmi PM, Kunjomana AG, Chandrasekharan KA, Meena M, Mahadevan CK. Structural, electrical and mechanical properties of GaTe for radiation detector applications. Int. J. Soft Comput. Eng., 2011, 1(5): 228

[6] Coskun C, Biber M, Efeoglu H. Temperature dependence of current-voltage characteristics of Sn/p-GaTe Schottky diodes. Appl. Surf. Sci., 2003, 211(1–4): 360.

[7] Mancini AM, Manfredotti C, Rizzo A. Vapour growth of GaTe single crystals. J. Cryst. Growth, 1974, 21(2): 187.

[8] Gadzhiev VA, Abdullaev B, Guseinova ES, Tagiev BG. On the electric conductivity of GaTe single crystals with tin impurities in strong electric fields. Phys. Status Solidi A, 1970, 2(3): 463.

[9] Balitskii OA, Jaeckel B, Jaegermann W. Surface properties of GaTe single crystals. Phys. Lett. A, 2008, 372(18): 3303.

[10] Pal S, Bose N. Growth, characterisation and electrical anisotropy in layered chalcogenides GaTe and InTe. Solid State Commun., 1996, 97(8): 725.

[11] Wagner RS, Ellis WC. Vapor-liquid-solid mechanism of single crystal growth. Appl. Phys. Lett., 1964, 4(5): 89.

[12] Raghavan PS, Ramasamy P. Crystal Growth: Processes and Methods, 1999, Kumbakonam, K.R.U. Publications, 404

[13] Chikawa JI, Nakayama T. Dislocation structure and growth mechanism of cadmium sulfide crystals. J. Appl. Phys., 1964, 35(8): 2493.

[14] Dierssen GH, Gabor T. Growth mechanism of CdS platelets. J. Cryst. Growth, 1972, 16(2): 99.

[15] Tang J, Alivisatos AP. Crystal splitting in the growth of Bi₂S₃. Nano Lett., 2006, 6(12): 2701.

[16] Gupta VP, Srivastava VK. Opto-electronic properties of gallium chalcogenides. J. Phys. Chem. Solids, 1981, 42(12): 1071.

[17] Nassary MM. Peculiarities of electric and thermoelectric properties of GaTe. Turk. J. Phys., 2006, 30, 95

[18] Desai CC, Ramana MSV. Growth and properties of ferroelectric lead hydrogen phosphate and lead nitrate phosphate single crystals. J. Cryst. Growth, 1988, 91(1–2): 126.

[19] Onitsch EM. Systematic metallographic and mineralogic structures. Mikroskopie, 1950, 5(3–4): 94