Silver-related local centres in cadmium sulfide

Silver-related defects and their diffusion in CdS crystals were investigated. The impurity was introduced in the crystal and extracted from it under electric field Ed = 10² V/cm at T = 300-450°C both parallel and perpendicular to the c-axis. The only local centre that was proved to appear after Ag introduction and to disappear after its extraction was deep acceptor responsible for emission band λm = 610 nm. Photo-enhanced defect reaction resulting in photosensitivity degradation was shown to occur after Ag incorporation. It was found that diffusion anisotropy took place, Ag diffusion being some times faster parallel to the c-axis

About the nature of diffusion anisotropy in CdS crystals

Electrodiffusion of copper into nominally undoped high-resistivity CdS crystals at 250-400°C has been investigated. A strong diffusion anisotropy has been observed, copper diffusion in perpendicular to the c-axis direction being more than one order faster as compared with its diffusion in parallel to the c-axis direction. The effect has been shown to be not due to greater density of perpendicular to the c-axis dislocations than that of parallel to the c-axis ones, as it was thought earlier. Electrically active dislocations lying in the basal plane are supposed to be channels of fast diffusion owing to their intensive decoration with intrinsic defects and residual impurities

Role of Ionic Processes in Degradation of Wide-Gap II-VI Semiconductor Materials

A role of mobile defects in processes responsible for II-VI compound semiconductor characteristic instability is under consideration. These defects have been shown to be responsible for electron-enhanced reactions in these materials, in particular, shallow donor creation in CdS crystals. Accumulation of mobile defects near dislocations results in some specific effects: anisotropy of conductivity induced by electric field and distortion of edge emission spectrum shape. These effects side by side with electron-enhanced defect reactions have been found to influence considerably semiconductor device characteristics