Behavior of temperature dependent electrical properties of Pd/Au Schottky contact to GaN grown on Si substrate by MBE

We investigated the effect of temperature on the behavior of electrical properties of Pd/Au Schottky contact to GaN/Si (111) in the temperature range of 125-325 Kin steps of 25 Kusing current-voltage (I-V) and capacitance-voltage (C-V) analysis. The Schottky barrier height (phi(I-V)) and ideality factor is calculated using standard thermionic emission theory. The value of fI-V was found to increase from 0.41. +/- 0.002 eV to 0.79 +/- 0.008 eV when temperature varied from 125 to 325 K. The ideality factor of diodes also decreased from 5.91 +/- 0.01 to 1.03 +/- 0.05 with increase in temperature. The series resistance (R-s) is calculated using Cheung's method and it is observed that the value of Rs decreased from 74.40 +/- 0.32 Omega to 58.59 +/- 0.11 Omega when the temperature increased from 125 to 325 K. Barrier height (phi(C-V)) and effective carrier concentration (N-d) is also reported from C-V characteristics as a function of temperature and the value of fC-V was found to decrease with increase in temperature. The behavior of barrier heights obtained from I-V and C-V characteristics is different due to difference in the nature of measurement techniques. The deviation of conventional Richardson's constant from theoretical value of GaN is due to unusual behavior of temperature dependent electrical properties and barrier inhomogeneity. This is successfully explained by assuming the double Gaussian distribution of inhomogeneous barrier heights of Au/Pd/GaN/Si Schottky diode.