Properties of Al/p-CdTe schottky barriers

Al/p-CdTe Schottky barriers diodes were prepared from the Te (1̄1̄1̄) face of lightly doped p-type CdTe single crystals. The characteristics of the diodes have been found to depend strongly on the surface preparation of CdTe. The current-voltage characteristics of diodes prepared from Br2-CH3OH etched surfaces are dominated by the tunneling mechanism with high saturation current densities. The use of Br2-CH3OH etch followed by heating in hydrogen has pronounced effects on the diode quality factor and saturation current densities due to the restoration of the surface stoichiometry. The C-V measurements at 1 and 10 MHz indicate that Schottky diodes prepared from Br2-CH3OH etched and 450 °C hydrogen-annealed CdTe have a barrier height of 0.76 V and that diodes prepared from Br2-CH3OH etched or lower-temperature hydrogen-annealed CdTe show larger barrier heights. In latter cases, the barrier height appears to be controlled by the metal-semiconductor interface states. In Al/p-CdTe Schottky barriers with low interface state density, the temperature dependence of the saturation current density suggests that diffusion is the dominant mechanism of current transport, due presumably to the low carrier density in CdTe.