A soft-solution electrochemical processing technique for preparing CdTe/n-Si(1 0 0) heterostructures

The rear side of an n type (1 0 0) Si wafer polished on one side was chosen as a substrate for CdTe thin film electrodeposition because its high density of surface non-uniformities is expected to result in a macroscopic equalization of injection conditions for electrons along the surface and subsequent uniform deposit growth. The films were grown from a plating bath containing 5 mM TeO2, 0.5 M CdSO4, 0.5 M H2SO4 and 0.5 M NH4F at a temperature of 85 °C. The deposition potential was selected after studying the electrochemical behavior of the precursors by cyclic voltammetry. EDS analysis showed that films with near stoichiometric composition were obtained at ca. −0.575 V vs SCE. XRD showed that the as deposited films are well crystallized with a preferential orientation along the [1 1 1] cubic direction, whereas AFM images show uniform and compact morphology. XPS results revealed that Te–O bonds, mainly in the surface, are also present.