Ternary II-VI semiconductors, like CdS_xSe_1-x or Zn_xCd_1-xS, were prepared by thermal evaporation of binary semiconductors from a double source. The influence of substrate temperature during thin film deposition and of thermal annealing in argon atmosphere on absorption edge steepness is studied. A high absorption edge steepness is advantageous to achieve large resonant optical nonlinearities, like absorption bistability and electronic nonlinearities. The position of the absorption edge can be tuned by choosing a proper film composition. Thermally induced optical bistability is demonstrated. Electronic nonlinearities are investigated in ns- and ps-pump-probe experiments. Fast bleaching with < 60 ps relaxation time is observed at the absorption edge. The maximum bleaching coefficient for CdS_0.69Se_0.31 films is 1.4 cm/kW at (lambda) equals 587 nm for pumping with (lambda) equals 377 nm. Annealing the films showed no effect on the relaxation time, but the bleaching coefficient was increased by a factor of five.

Date Published: 4 March 1993
PDF: 9 pages
Proc. SPIE 1782, Thin Films for Optical Systems, (4 March 1993); doi: 10.1117/12.141008

Published in SPIE Proceedings Vol. 1782:
Thin Films for Optical Systems
Karl H. Guenther, Editor(s)