Vapor chloride treatment of polycrystalline CdTe/CdS films

Heat treatment with CdCl₂ near 400°C has been known to consistently improve the electronic properties of thin-film CdTe. The treatment process usually involves application and drying of the CdCl ₂ solution, annealing and residue removal. The conventionally treated films often appear non-uniform with insoluble Cl-containing residues. In order to make the process more suitable to manufacturing alternative methods have been investigated. CdCl₂ vapor, hydrogen chloride and chlorine gases have been applied to treat CdTe/CdS films. The vapor CdCl₂ and hydrogen chloride treated CdTe surface are found to be uniform with little Cl-related residues and to have electronic properties similar to the conventionally treat films. Total area efficiency of 6.9% has been demonstrated on a CdCl₂ vapor treated 7200 cm² module