Chemically-deposited Te layers improving the parameters of back contacts for CdTe solar cells

A chemical bath process was carried out for the deposition of Te layers on CdTe films grown by the close-space vapor transport technique (CSVT) on conducting SnO2:F substrates. The Te layers were chemically-deposited on as-grown CdTe films and on previously CdCl2-treated CdTe ones. After Te deposition, the CdTe films were annealed at temperatures from 200 to 400 °C. The Te layer on top of the CdTe films was studied by Raman Spectroscopy and by Scanning Electron Microscopy. The electrical resistivity of the annealed CdTe films was determined from current versus voltage measurements in a sandwich configuration, employing gold contacts on top of the CdTe modified surface. The results show that the combined effect of the Te layer on CdTe together with previous CdCl2 treatment improves the electrical properties of CSVT-CdTe films. These results are quite promising for increasing performance of CdS/CdTe solar cells.