Electronic States of Grain Boundaries in Bicrystal Silicon

Electronic states at a 20° symmetrical(100) tilt boundary in p-type silicon were studied using deep level transient spectroscopy (DLTS) and other electrical measurements. The data can be explained with a model in which the local barrier height at the grain boundary varies on a scale much smaller than the boundary plane (∼I mm2) under study. Based on a relationship between the carrier capture cross section and energy level deduced from the experimental data, we have been able to calculate the distribution of the density of states in the energy bandgap at the boundary, which contains two groups of continuously distributed states; a major one whose density of states increases monotonically with the position of the state from the valance band, and a minor narrow one whose density of states is centered at Ev,+0.20 eV.