Photoenhanced dissolution and diffusion of Ag in As 2S x layers

Abstract

Abstract The photoenhanced dissolution and diffusion (PD) of Ag in AsS layers was studied. The time dependence of PD rate is of sigmoid type and is influenced by the intensity of illumination, wavelength of actinic light and by the composition of layers. The induction period is shortened when Ag 2 S or an Ag-doped interlayer is placed between silver and the undoped AsS layer. It is proposed that during the induction period a new photodoped amorphous phase II with high Ag content is formed. Sharp diffusion profile of Ag is caused by the existence of an immiscibility gap of Ag in the AsS system. The rate of PD in the linear part of the sigmoid curve is controlled by a diffusion field (Nernst potential) created by different mobilities of Ag + ions and holes (electrons). The diffusion of mobile Ag + is controlled by diffusion of low mobility holes (electrons). The illumination increases their density, decreases the diffusion potential and speeds up the diffusion rate of Ag + ions.