Au/P polysilicon Schottky diodes

Schottky barrier diodes were fabricated by evaporation of gold layers onto chemically etched polycrystalline silicon wafers. The wafers are p type (resistivity ρ⊥=160 Ωcm, the grains are columnar shape with some orientation). An average potential barrier of 0.087 eV appears to exist across the grain boundary between columns. Ohmic back contacts were made from a Ga-Al alloy. Diodes were investigated with the aid of (a)I-V characteristics at different temperatures, (b)C-V characteristics, (c) spectral response and (d) Fowler's plot of photoelectric measurements. The best diodes had characteristics similar to data typical of monocrystalline silicon. The low series columnar resistance (0.67Ω) of the cells is neglected in the analysis. The barrier height, from I-V data (including temperature variation) was 0.67 to 0.73 eV. This is much lower than that obtained from Fowler's plot (0.9 eV). However, the barrier height obtained from the C-V graph is in agreement with the value of 0.9 eV. The diffusion potential is 0.4 eV. The value of the diode ideality factor (1.5 to 2.8) indicates that recombination generation processes play a dominant role. The normalized photovoltaic spectral response in the wavelength range 600 to 1300 nm was presented with a comparison from the theory taking into account bulk and surface recombination. © 1989 Chapman and Hall Ltd.