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FIZIKA A 6 (1997) 3, 111-120
 
OPTICAL CHARACTERISTICS OF BISMUTH SULFIDE (Bi2S3)
THIN FILMS
S. MAHMOUD, A.H. EID, and H. OMAR
Physics Department, National Research Centre, Cairo, Egypt
Received 19 May 1997
Revised manuscript received 15 September 1997
Thin films of bismuth sulfide (Bi2S3) were grown by two
deposition techniques, by thermal evaporation and by chemical deposition. The thermally
deposited reactions consisted in depositing the individual elements, namely bismuth and
sulfur, sequentially from a tungsten boat source and allowing the layers to interdiffuse
to form the compound during the heat-treatment. The chemical deposition was based on the
reaction between the triethanolamine compex of Bi3+ ions and thiourea in basic
media. Scanning electron microscope and X-ray diffraction analysis were made on
as-deposited and on annealed films to determine their structure. The different electronic
transitions and the optical constants are determined from the transmision and reflection
data of these thin films for normal incidence. The optical gaps of Bi2S3
films show a remarkable dependence on the preparation method.
UDC 538.975
PACS numbers 73.40.-c, 78.66.-w
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