Electrochemical atomic layer deposition of a CdTe/PbTe superlattice for the absorber layer of a solar cell

Electrochemical Atomic Layer Deposition (ECALD) has been used to deposit CdTe and PbTe thin films. CdTe and PbTe are of interest in forming a superlattice structure to be used in the absorber layer of a solar cell. Cyclic voltammetry was used to study the Underpotential Deposition (UPD) of the constituent compounds. Pb was grown at a constant -0.35V vs. Ag/AgCl reference electrode.. Te deposition potential was varied from -0.55V to -0.4V. Cd was deposited at -0.55V and Te was deposited at -0.8V. The coverage of the films was estimated using the coulometry method. The chemical composition of the films was characterized using Energy-Dispersive X-ray Spectroscopy (EDS) on a Scanning Electron Microscope (SEM). The crystallinity of the films was studied using a glancing angle x-ray diffractometer. The bandgaps of the films were determined using optical reflection data.