Barrier-limited carrier transport in highly n-doped μc-Si:H thin films

Hall mobility data for highly n-doped μc-Si:H thin films are quantitatively analyzed in an attempt to understand the role of grain boundaries in carrier transport in microcrystalline materials. Model calculations are performed for samples made up of a linear chain of identical grains. Within the trapping model, band edge profiles are calculated by solving the non-linear Poisson equation. Tunneling is taken into account in a fully quantum-mechanical treatment. Barrier heights are deduced from the experimental data by adjusting the trapping-state density. Owing to the sizeable effect of tunneling, these heights are substantially larger than the activation energies of the Hall mobilities.