Temperature dependence of electrical transport properties of n‐type solar grade polycrystalline silicon Available to Purchase

The effect of temperature on the electronic conduction mechanism and grain‐boundary states has been observed through the measurements of Hall coefficient (R_H), resistivity ( ρ), and Hall mobility (μ_H=R_H/ρ), on n‐type solar grade polycrystalline silicon having columnar grains in the temperature range ∼77–500 K. It is found that electronic conduction in the low‐temperature range is determined by the hopping of the charge carriers in the localized states at the Fermi‐level and R_H is a slow function of temperature. In the intermediate temperature range the conduction is dominated by the thermionic emission of electrons over the grain boundaries. At a critical temperature T_c where the barrier height (φ_b) and hence the width of the space‐charge region near the grain boundaries tends to zero, a crossover from the barrier‐limited to the mobility‐limited resistivity occurs. R_H is found to be thermally activated over the temperature range where the conduction mechanism is governed by grain‐boundary barriers. The experimental results are explained on the basis of a grain‐boundary trapping model combined with the two‐phase model and are used to determine various parameters, viz., grain size, trap‐state density, and the amount of band bending at the grain boundary.