Structure and Characteristics of Silicon Carbide Light-Emitting Junctions

Abstract

Current‐voltage characteristics of SiCp‐n junctions have been measured on light‐emitting samples prepared in such a way as to minimize leakage at the periphery and through ``blue spots.'' The characteristics of such junctions are found to be very different from those previously reported. We deduce from the characteristics that these junctions have a p‐n*‐n structure rather than a p‐n structure. The high resistivityn* layer is essential for the observed light‐emission. This layer, together with the blue spots which short circuit the p‐n* junction, determines the form of the reverse characteristic. Two portions of the reverse characteristic take their form from space‐charge‐limited currents in the n* layer. A theory is given of the forward characteristic of the p‐n*‐n structure and compared with the experimental I‐V curve. The theory permits one to obtain a value of the thermal energy gap from a forward characteristic at a single temperature. From a fit of our data the energy gap is found to be 2.83±0.1 ev at room temperature. Results of some experiments on crystal growing are presented and an explanation of the manner of growth of light‐emitting junctions is suggested.