FIZIKA A 5 (1996) 4, 205-213

OPTICAL AND ELECTRICAL PROPERTIES OF BISMUTH-SULFIDE (Bi₂S₃) THIN FILMS PREPARED BY THERMAL EVAPORATION

SIHAM MAHMOUD and FOUAD SHARAF

Faculty of Science, Suez Canal University Physics Department, National Research Center, Dokki, Cairo, Egypt

Received 10 January 1997

Thin films of Bi₂S₃, of thickness in the range 300 to 500 nm, were produced by thermal evaporation technique. The reaction consisted in depositing the two elements (bismuth and sulfur) from a boat source and allowing their atoms to interdiffuse to form the compound during the deposition on quartz substrates. The material has been characterized by X-ray studies, optical and electrical measurements. When these films were annealed at 353 K, 393 K and 453 K for 5 hours, a nearly amorphous to polycrystalline transition was observed. The absorption coefficient revealed the existence of an allowed direct transition with E_g = 1.56 eV. The activation energies for electrical conduction in low and high temperature regions are 0.28 eV and 0.73 eV, respectively.

UDC 538.975
PACS 73.40.-c, 78.66.-w

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