Electrochemical Deposition, Optical Properties, and Photoelectrochemical Behavior of CdTe Films

Abstract

Electrochemical deposition of cadmium telluride from acidic solutions containing CdSO4 and TeO2 is studied and the current‐potential expression for this reaction is presented. The electrochemically deposited normalCdTe films are photoactive, and the maximum cathodic photocurrent due to hydrogen evolution is observed at normalCdTe films deposited at −0.40V. The photocurrents of the as‐grown normalCdTe films are relatively small compared with those of normalCdTe single crystals. The major reason for this low efficiency is the effective recombination of hole‐electron pairs at grain boundaries and at the surface. The photocurrents are increased significantly by the increase of crystallite diameter by the heat‐treatment in a He atmosphere and by the removal of surface Te, which acts as a recombination center, by the etching treatment.

Photoelectrochemical Generation of Hydrogen at Electrochemically Deposited p ‐ CdTe Films: Effect of Heat‐Treatment, Surface Modification by Platinum and Surface Oxide Layer on Conversion Efficiency

“…The semiconductivity of the films treated for 7h was hard to be determined and that of those treated for longer than 8h was n-type. As already reported, if the films were treated at 200~ the films remained p-type with the x-ray diffraction peak due to free Te even after 12h treatment (14).…”

“…We have recently investigated the electrochemical deposition of CdTe thin films from the solution containing CdSO~ and TeO2 and reported the effect of preparation conditions, e.g., deposition potential, on the composition and optical and electronic properties of the deposited films (12)(13)(14). We also studied the photoelectrochemical generation of hydrogen at the electrochemically deposited p-CdTe films (12,14). The conversion efficiency at the as-grown films was poor compared with that at single crystal electrodes.…”

Some Experimental Aspects of the Cadmium‐Tellurium Electrochemical Codeposition Process

“…The etch process is an important aspect of semiconductor-electrode pretreatment and has been investigated by a number of authors for CdTe photovoltaic materials. Takahashi et al (12) noted a similar relationship between the etching process and the photoresponse for CdTe electrodes. Gaugash and Milnes (26) tested ten different etch solutions for CdTe electrodes.…”

“…Thin films of CdTe have been prepared by chemical vapor deposition, vacuum evaporation, and electrodeposition processes. As is the case in the present study, most Cd-Te codeposition processes make use of an aqueous, cadmium sulfate, tellurium dioxide, sulfuric acid electrolyte (3)(4)(5)(6)(7)(8)(9)(10)(11)(12). 2 Since the costs associated with thin-film electrodeposition processes are generally less than the previously mentioned fabrication techniques, this study is particularly relevant to the fabrication of large area, CdTe solar cells.…”

In-Situ STM Study of Te UPD Layers on Low Index Planes of Gold

“…Epitaxial films of II−VI semiconductor compounds such as cadmium telluride are promising candidates in solar cell applications and infrared detection . A major thrust of recent research has been dedicated to studying their formation by cathodic electrodeposition from aqueous solutions − as this method provides an attractive, low cost, ambient temperature approach to the fabrication of these devices. Most of the previous Cd/Te electrodeposition studies, however, have resulted in amorphous and polycrystalline deposits with extensive grain boundaries leading to an increased resistivity of these materials .…”