Temperature-dependent electrical properties of (Pt/Au)/Ga-polarity GaN/Si(1 1 1) 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 (ϕB0)(ϕB0) and ideality factor (‘n’) were extracted from I–V   using standard thermionic emission (TE) theory. The estimated ϕB0ϕB0 and ‘n’ are found to be 0.50 eV and 3.2 for 200 K, 0.78 eV and 1.4 for 375 K. The calculated series resistance (Rs) by Cheung’s method shows unusual behavior with increasing temperature. The Rs value exhibits by diode at 200 K is about 534 Ω, which then decreases to 132 Ω for 300 K and thereafter increases to 154 Ω at 375 K, respectively. It was seen that ϕB0ϕB0, ‘n’ and Rs   are strongly temperature dependent. There is also a linear correlation between ϕB0ϕB0 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 ∼5.57 × 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 (Φ¯) is 1.04 eV and standard deviation (σs) to be 145 mV. In addition to this, obtained A∗ from the modified Richardson plot ln(Js/T2)-(e2σ02/2k2T2)versus 1/T is 27.62 A cm−2 K−2, which is in good agreement with the theoretical value of GaN.

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