INVESTIGATION OF THE INFLUENCE OF THE ELECTRODEPOSITION POTENTIAL ON THE OPTICAL, PHOTOELECTROCHEMICAL AND STRUCTURAL-PROPERTIES OF AS-DEPOSITED CDTE

The electrodeposition of cadmium telluride on cadmium sulphide deposit ed from a chemical bath is investigated with the aim of improving the structural and optical properties of the CdTe layers for solar cell ap plications. The CdTe layers are characterized by X-ray diffraction spe ctroscopy, optical transmission measurements and photoelectrochemical measurements. The influence of the electrodeposition potential on the conductivity type of the deposited CdTe is demonstrated. Spectral resp onse measurements are used as an analytical method to study the optoel ectronic properties of CdTe. Thickness-dependent spectral responses re flect a change of doping type for electrodeposition potentials more po sitive than +5 mV vs. the deposition potential of elemental cadmium. A front- and back-side illumination technique is used to determine the position of the active junction which varies between a n-CdS/p-CdTe an d a n-CdTe\electrolyte junction. The width of the space charge layers and the doping concentrations are determined by using the Gartner equa tion for fitting the quantum efficiency vs. absorption coefficient plo ts.