STRUCTURAL AND ELECTRICAL-PROPERTIES OF ANNEALED IN-BI2S3 THIN-FILMS

Intrinsic bismuth sulfide deposited on indium thin films (similar to 2 0nm) change to n-type when annealed in air or nitrogen atmosphere. As deposited bismuth sulfide on the In films is amorphous and electricall y very resistive, Annealing the films in air at 200, 300, and 400 degr ees C results in the formation of In2O3 as observed in the X-ray diffr action patterns of the films. The dark conductivity of the In + bismut h sulfide films nitrogen-annealed at 300 degrees C attains a value of 600 Ohm(-1) cm(-1), which is an improvement by more than eight orders of magnitude compared with as-prepared films. This improvement is attr ibuted to amorphous-crystalline transformation and the presence of met allic bismuth and In2O3 in the annealed films. An etching test in 1 M solution of HCl indicates that these films are rather stable in acid m edium. (C) 1998 Academic Press.