Screen-printed p-CdTe layers for CdS/CdTe solar cells

Correlation of the recrystallization process technological parameters with the morphology and structure of screen-printed p-CdTe layers intended for CdS/CdTe solar cell fabrication has been established. The optimal regimes to form layers with required characteristics have been found. As distinct from the used previously screen-printing techniques for CdS/CdTe solar cell fabrication, CdTe layers were doped with Ag or Au not by their diffusion from the layer surface but in the course of layer preparation. For this purpose, tellurides of those metals were added into the raw paste used for CdTe screen printing. It is shown that the developed method has some advantages and allows to prepare CdTe films, structural and electrophysical parameters of which are suitable to fabricate CdS/CdTe solar cells

Recrystallization processes in screen-printed CdS films

Kinetics of recrystallization in screen-printed polycrystalline CdS films has been investigated by X-ray structure analysis and optical microscopy. The relation between the crystallite size, crystallite orientation and the macrostrain, as well as their dependence on heat treatment regimes is established. It is shown that single-phase CdS films having a thickness of some tens microns, large grain size and low residual strain can be produced at optimum technological regimes. The films obtained are suitable for fabrication of CdS/CdTe solar cells

Large polycrystalline optical germanium Ge:Na plates with improved optical parameters and their application

It has been experimentally shown that transmission and scattering of IR radiation by Na-doped соarse-grained large germanium plates are the same as of Ge:Na single crystals and exceeds the parameters in the commonly used optical germanium Ge:Sb grown from the same raw material. Being based on experimental results, a conclusion has been made that the nature of the dopant in Ge:Na is a decisive factor defining its optical parameters, along with the usual requirements of high purity of the raw material, resistance values below about 20 Ohm·cm and a sufficiently large grain size (for polycrystalline material). It is assumed that, most likely, Na in Ge:Na, contrary to Sb in Ge:Sb, doesn’t form impurity clouds that scatter the incident IR radiation. The advantages of the polycrystalline Ge:Na as a material for IR optics were proved when using it for industrial manufacturing the protective screens for night vision systems

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