Temperature-dependent electrical properties of (Pt/Au)/Ga-polarity GaN/Si(111) Schottky diode

We report on temperature dependent electrical properties of (Pt/Au)/Ga-polarity GaN/Si(1 1 1) Schottky diode using current-voltage characteristics in the temperature range of 200-375 K. The basic diode parameters, such as zero-bias Schottky barrier height (phi(B0)) and ideality factor ('n') were extracted from I-V using standard thermionic emission (TE) theory. The estimated phi(B0) and 'n' are found to be 0.50 eV and 3.2 for 200K, 0.78 eV and 1.4 for 375K. The calculated series resistance (R-s) by Cheung's method shows unusual behavior with increasing temperature. The Rs value exhibits by diode at 200 K is about 534 0, which then decreases to 132 0 for 300 K and thereafter increases to 154 Omega at 375 K, respectively. It was seen that phi(B0), 'n' and R-s are strongly temperature dependent. There is also a linear correlation between phi(B0) and 'n' due to the inhomogeneities of the barrier heights (BHs). The estimated Richardson's constant (A*) from intercepts at the ordinate of linear fit to the conventional activation energy plot is about similar to 5.57 x 10(-3) A cm(-2) K-2,which is much lower than the known value of n-type GaN (26.4 A cm(-2) K-2). Such behavior is also attributed to barrier inhomogeneities at the contact interface. In order to prove the same, results have been interpreted based on the assumption of Gaussian distribution (GD) over the BHs. We calculated the mean barrier height ((Phi) over bar) is 1.04 eV and standard deviation (as) to be 145 mV. In addition to this, obtained A* from the modified Richardson plot In(J(s)/T-2) - (e(2)sigma(2)(0)/2k(2)T(2)) versus 1/T is 27.62 A cm(-2) K-2, which is in good agreement with the theoretical value of GaN. Crown Copyright (C) 2011 Published by Elsevier B.V. All rights reserved.