Carrier Transport across a Few Grain Boundaries in Highly Doped Polycrystalline Silicon

We have fabricated nanometer-scale point-contact devices in 50-nm-thick poly-Si films with a grain size of from 150 nm to 20 nm. Both linear and nonlinear I ds-V ds characteristics were observed in these devices, corresponding to a channel without a grain boundary (GB) and that with a single or a few GBs, respectively. The temperature dependence of resistivity indicated that the effective potential barrier height q V B of the GBs for the devices which show the nonlinear I ds-V ds characteristics ranges from 30 meV to 80 meV. We discussed percolation conduction of electrons through a few GBs due to nonuniform GB properties in heavily doped poly-Si films.