Paper AS-WeM1
Probing Photoinduced Charging in CdS and CdSe Films by Dynamical XPS Measurements

Wednesday, November 11, 2009, 8:00 am, Room C2

Photoconductive materials have gained renewed interest in recent years due to the advancements in controlling their electronic and optical properties, which exhibit strong size, shape and chemical composition dependence. Recently, we have developed a technique for recording the shifts in the positions of the XPS peaks in response to different forms of electrical stimuli for probing dynamics of charging/discharging processes in thin dielectric films, which we have named as Dynamical XPS. In the present contribution, we introduce photoillumination as an additional form of stimuli and investigate the combined optical + electrical response of thin CdS and CdSe films deposited on silicon substrates containing ca. 5 nm thermal oxide layer. Modulation of the electrical signals in the forms of square, sinusoidal and triangular waves at different frequencies enables us to extract some dielectric properties of the SiO₂ and CdS (or CdSe) surface structures both under and without photoillumination. Experimental results will be presented, discussed, and compared with those of simulations.