Current Flow across Grain Boundaries in n-Type Germanium. II

Abstract

The current flow across grain boundaries in n‐type germanium has been measured in the temperature range of 350−200°K. Precisely oriented bicrystals have been grown for this study with 4, 6, and 25° tilt boundaries and 6° twist boundaries. The experimental data were found to be in good agreement with theoretical calculations given in the accompanying article [R. K. Mueller, J. Appl. Phys. 32, 635 (1961)]. The current across the boundary is mainly carried by electrons crossing the barrier, and it increases with decreasing boundary angle. The activation energy was found to be 0.71±0.01 ev for all boundaries. A lower limit of N_B≥10¹³ (cm⁻² ev⁻¹) was found for the density of boundary states of 6 and 25° boundaries. No significant difference between tilt and twist boundaries has been observed.