C-V-f, G-V-f and Z ''-Z ' Characteristics of n-Type Si/B-Doped p-Type Ultrananocrystalline Diamond Heterojunctions Formed via Pulsed Laser Deposition

摘要

n-Type Si/p-type B-doped ultrananocrystalline diamond heterojunction photodiodes were built using pulsed laser deposition at a heated substrate temperature of 550 degrees C. Following the capacitance-voltage-frequency (C-V-f) and conductance-voltage-frequency (G-V-f) plots, the series resistance (R-s) values at zero bias voltage were 154.41 Omega at 2 MHz and 1.72 k Omega at 40 kHz. R-s should be ascribed to R-s occurring in the metallic contact and the bulk resistance in the active layer. At 40 kHz, the interface state density (N-ss) was 1.78x10(13) eV(-1) cm(-2) and dropped exponentially to 1.39x10(12) eV(-1) cm(-2) at 2 MHz. An assessed Nss occurring at the heterojunction interface was the cause of deterioration in the photo-detection properties. At different V values, the appearance of the real (Z') and imaginary (Z '') characteristic curves revealed single semicircles whose centers lay below the Z' axis. The magnitude of the curve was diminished with the increment of V. The particularities of Z ''-Z ' plots can be identified as an equivalent circuit model. The appropriate model included Rs, which was combined with the parallel circuit of resistance and constant phase element.