Effect of Sc and Yb doping on electrical and luminescence properties of silicon produced by the Stockbarger method

Abstract

The effect of scandium and ytterbium doping on the electrical and luminescence properties of polycrystalline silicon produced by the Stockbarger method was studied. It is found that the resistivity, the lifetime of minority charge carriers, and the position of the maximum of the low-temperature luminescence band, which are constant along the growth direction for undoped ingots, vary monotonically along the growth direction for doped ingots. Analysis of the photoluminescence spectra and conductivity in different parts of the doped ingots shows that variations in their electrical properties along the growth direction are due to a redistribution of background acceptors, whose concentration decreases steadily from the beginning of an ingot toward its end. The redistribution of the background impurities is related to the formation of background-impurity-doping impurity compounds, for which the distribution coefficients significantly deviate from unity in a silicon melt.