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 th e plasma and on room temperature substrates in order to be used as ant ireflective coating on GaAs solar cells. The electrical resistivity of the n-type, degenerate ITO films exhibited a reduction with depositio n rate and an increase with total pressure, while it was independent o f the film thickness in the range of 20 nm to 130 nm. Further reductio n of resistivity, up to 4 x 10(-4) Ohm cm, was obtained by annealing a t 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 ce ll was reduced from 35% to 2% after the ITO layer application.