Photoinduced Dichroism in Amorphous As2Se3 Thin Film
Several aspects of photoinduced anisotropy in a-As2Se3 have been analyzed:
(i) rate of photoinduced anisotropy buildup as a function of inducing beam intensity and sample thickness,
(ii) the kinetics of the photoinduced anisotropy buildup in terms of a stretched exponential curve,
(iii) the stretched exponent, ?, as a function of inducing beam intensity and sample thickness,
(iv) reversibility of the photoinduced anisotropy, (v) saturation level of photoinduced anisotropy as a function of inducing beam intensity and sample thickness.
The anisotropy buildup kinetics has been found to follow a stretched exponential behavior and that there exists an inverse relationship between the pump intensity and the time constant, ?. The ?(I) vs intensity (I) relationship more closely follows a logistic dose response curve than a simple straight line or power law relationship. There exists a direct relationship between the time contact ? and the sample thickness, where a longer anisotropy buildup time is required as the sample thickness increases. The stretched exponent, ?, was found to be approximately 0.6 and has a slight dependence on the inducing light intensity. The correlation of the stretching exponent, ?, to sample thickness, L, was found to have a weak inverse relationship, that is ? tends to decrease as the sample thickness increases.
The findings in this work demonstrate that the anisotropy orientation could be changed indefinitely since it was found that even after 100 orientation changes the anisotropy saturation had no measurable fatiguing. The anisotropy saturation level was found to be independent of the inducing beam intensity and linearly proportional to the sample thickness.
Advisor:Xiao, Chijin; Teng, Hsiang-Yung (Daniel); Kasap, Safa O.; Daku, Brian L.; Johanson, Robert E.; Bolton, Ronald J.
School:University of Saskatchewan
School Location:Canada - Saskatchewan
Source Type:Master's Thesis
Keywords:photoinduced dichroism anisotropy amorphous thin film
Date of Publication:12/20/2005