Study of barrier inhomogeneities using I–V–T characteristics of Mo/4H–SiC Schottky diode

Abstract In the present work we investigate the forward current–voltage ( I–V ) characteristics, over a wide temperature range 298–498 K, of Mo/4H–SiC Schottky diode for which aluminum ion implantation was used to create the high resistivity layer forming the guard ring. The ( I–V ) analysis based on Thermionic Emission (TE) theory shows a decrease of the barrier height ϕ B and an increase of the ideality factor n when the temperature decreases. These anomalies are mainly due to the barrier height inhomogeneities at the metal/semiconductor interface as we get a Gaussian distribution of the barrier heights when we plot the apparent barrier height ϕ ap versus q / 2kT . The mean barrier height and the standard deviation obtained values are ϕ ¯ B0 =1.160 eV and σ 0 =88.049 mV, respectively. However, by means of the modified Richardson plot Ln ( I s / T 2 ) − ( q 2 σ 0 2 / 2 k 2 T 2 ) versus q / kT , the mean barrier height and the Richardson constant values obtained are ϕ ¯ B0 =1.139 eV and A * =129.425 A/cm 2  K 2 , respectively. The latter value of ϕ ¯ B0 matches very well with the mean barrier height obtained from the plot of ϕ ap versus q / 2kT . The Richardson constant is much closer to the theoretical value of 146 A/cm 2  K 2 . The series resistance R s is also estimated from the forward current–voltage characteristics of Mo/4H–SiC Schottky contact. This parameter shows strong temperature dependence. The T 0 effect is validated for the 298–498 K temperature range for the used Schottky diode and provides a clear evidence for the barrier inhomogeneity at the Mo/4H–SiC interface. Finally, we note the impact of the implantation process as well as the choice of the used ion on the characterized parameters of the Schottky contact.