Electron-transport mechanisms in metal Schottky barrier contacts to hydrogenated amorphous silicon

Detailed electrical studies have been carried out on nickel, palladium, and platinum Schottky barrier contacts to intrinsic a-Si:H films of 0.5, 1.0, and 3.0 μm thickness. The diode characteristics of the Schottky barrier structures are investigated using light and dark I-V measurements over a temperature range of 24–150 °C. The activation energies of the diode currents are compared to the electron barrier heights determined from internal photoemission (IPE) measurement. The bias dependence of the reverse diode currents is directly compared to the barrier lowering measured by IPE. The diode currents are explained in terms of a joint thermionic-emission/drift-diffusion model that includes changes in the barrier height with applied bias.