RF sputtered indium-tin-oxide as antireflective coating for GaAs solar cells

Conductive and antireflective indium-tin-oxide (ITO) has been prepared by RF sputtering in Ar atmosphere, without introducing oxygen into the plasma and on room temperature substrates in order to be used as antireflective coating on GaAs solar cells. The electrical resistivity of the n-type, degenerate ITO films exhibited a reduction with deposition rate and an increase with total pressure, while it was independent of the film thickness in the range of 20 nm to 130 nm. Further reduction of resistivity, up to 4 x 10(-4) Ohm cm, was obtained by annealing at 400 degrees C. This is the lowest resistivity that has been reported for ITO films prepared under similar conditions. The transmittance of 90 nm thick ITO film was 85% and the reflectance of p/n GaAs solar cell was reduced from 35% to 2% after the ITO layer application.