Sputtered CdTe thin film solar cells with Cu₂Te/Au back contact

In this work, Cu₂Te/Au back contact for CdTe thin film solar cells were prepared by vacuum evaporation. Influence of annealing temperature on the structure and electrical properties of Cu₂Te films were investigated by field emission scanning electron microscope, X-ray diffraction, and Hall effect measurement. Also, CdS/CdTe thin film solar cells were fabricated bymagnetron sputtering process, which is favorable for large area deposition and mass production, and the photovoltaic characteristics were studied. As the annealing temperature was increased, the crystal structure transformed from Cu₂Te for as-deposited film to Cu_{2 - x}Te hexagonal phase, and the grains in the film became bigger. The electrical resistivity was slightly higher by the annealing. The cell efficiency was significantly improved by the heat treatment, and showed a maximum value of 9.14% at 180 °C. From these results, Cu₂Te/Au contact acts as the proper pseudo-ohmic contact onto CdTe film. However, further increase of annealing temperature caused the deterioration of cell performance.