On the negative capacitance behavior in the forward bias of Au/n–4H–SiC (MS) and comparison between MS and Au/TiO2/n–4H–SiC (MIS) type diodes both in dark and under 200 W illumination intensity

Abstract

In order to see the effect of interfacial layer on electrical characteristics both Au/n-4H- SiC (MS) and Au/TiO<inf>2</inf>/n-4H-SiC (MIS) type Schottky barrier diodes (SBDs) were fabricated and their main electrical parameters were investigated by using the forward and reverse bias current-voltage (I -V ), capacitance/conductance-voltage (C/G-V ) measurements at room temperature. The ideality factor (n), series and shunt resistances (R<inf>s</inf>,R<inf>sh</inf>), barrier height (BH), depletion layer width (WD) and the concentration of donor atoms (ND) were obtained before and after illumination. The energy density distribution profile of surface states (Nss) was also obtained by taking into account voltage dependent effective BH (?<inf>e</inf>) and ideality factor (nV ). All of these experimental results confirmed that the use of a high dielectric material or insulator layer (TiO<inf>2</inf>) between metal and semiconductor leads to improvements in the diode performance in terms of Rs, Rsh, BH, Nss and rectifier rate (RR = IF /IR for sufficiently high forward and reverse current). Another important result is the negative capacitance (NC) behavior observed in the forward bias C-V plot for the Au/n-4H-SiC (MS) diode, but it disappears in Au/TiO<inf>2</inf>/n-4H-SiC (MIS) diode and also the minimum value of C-V plot corresponds to maximum value of G/w-V plot in the accumulation region. Such behavior of NC shows that the material displays an inductive behavior. © World Scientific Publishing Company.