The investigation of current-conduction mechanisms (CCMs) in Au/ (0.07Zn-PVA)/n-4H-SiC (MPS) Schottky diodes (SDs) by using (I-V-T) measurements

Abstract

The semi-logarithmic forward bias I-V plots of the Au/(0.07Zn-PVA)/n-4H-SiC (MPS) type SBDs showed double exponential behavior therefore these plots revealed two distinct linear regions which correspond to low (0.05 V ≤ 0.4 V) and moderate voltage regions (0.4 ≤ V ≤ 0.8 V) (LBR and MBR), respectively, for each temperature level. It was observed that the value of ideality factor (n) decreased with increasing temperature whereas opposite behavior occurred for zero-bias barrier height (ΦB0). The behavior of nkT/q vs kT/q plot for MBR indicated that a combination of thermionic field emission (TFE) and field emission (FE) mechanisms, i.e. the tunneling mechanism, may be dominant especially at low temperatures. In order to explain such unexpected behavior of the conduction mechanism; ΦB0 vs n, ΦB0 vs q/2kT and (n−1 − 1) vs q/2kT plots were drawn to obtain an evidence of a Gaussian distribution (GD) of the barrier heights (BHs) and all of them revealed two linear regions for both LBR and MBR. The conventional Richardson plot was modified by using the obtained standard deviation (σso) of BH from ΦB0 vs q/2kT plots for two bias regions. Thus, the mean BH (Φ̅B0) and effective Richardson constant (A*) values for LBR were calculated from the slope and intercept of the modified Richardson plots as 0.730 eV, 114.12 A cm−2 K−2 at low temperature range (100 ≤ T ≤ 200 K) and 1.304 eV, 97.33 A cm−2 K−2 at high temperature range (200 ≤ T ≤ 320 K), respectively. These values for MBR were found as 0.687 eV, 144.97 A cm−2 K−2 at low temperature range and 1.165 eV, 122.11 A cm−2 K−2 at high temperature range, respectively. It is clear that the values of A* for MBR at low temperatures are closer to 146 A cm−2 K−2 which represents the theoretical value of for n-4H-SiC. As a result, the current conduction mechanisms (CCM) in Au/(0.07Zn-PVA)/n-4H-SiC (MPS) SD can be successfully explained by thermionic emission (TE) mechanism with the double GD of BHs.