Gate Metal Dependent Reverse Leakage Mechanisms in AlGaN/GaN Schottky Diode

Abstract

The dependence of the gate leakage mechanism in the AlGaN/GaN Schottky diode on the metal–semiconductor (MS) interface state has been investigated. Schottky gates with Au, Pt, Pd, and Ni showed the remarkably different gate leakage mechanisms in the reverse direction. Through the analysis of the temperature dependent reverse leakage currents, it is shown that the discrete energy levels of MS interface states are the key factor in determining whether the leakage mechanism at the high temperature over 300 K is caused by the electron tunneling or by the Frenkel–Poole emission from the MS interface state to the conductive dislocation state.

AlGaN/GaN Heterostructure Schottky Barrier Diodes with Graded Barrier Layer

“…Figures 4(a) and 4(b) exhibit good Schottky diode properties of conventional and recessed ring SBDs. When the voltage is lower than the pinch-off voltage (V S < V r < 0 V), the currents gradually increase as the voltage increases due to the Frenkel-Poole (FP) emission mechanism [21,[28][29][30], and the channel carriers are not pinch-off at this time. In comparison with the S2 and S3, the S1 increases more slowly due to the thicker barrier width.…”

Current transport mechanism of AlGaN/GaN Schottky barrier diode with fully recessed Schottky anode

“…This indicates that there exists another leakage mechanism that also contributes to the total leakage current. To clarify the additional reverse leakage mechanism above the pinch-off voltage (¹5 V < V r < 0), the Frenkel-Poole (FP) emission [2][3][4] is considered. The current density associated with the FP emission is given by…”

“…where C is a constant, º t is the barrier height for the electron emission from the trap state, and ¾ s is the permittivity of the semiconductor at a high frequency. Equation ( 6) can be rearranged as [2][3][4] lnðJ…”

“…AlGaN/GaN-based Schottky barrier diodes (SBDs) and their current transport mechanisms have been intensively studied, [1][2][3][4][5][6][7][8][9][10][11] as they offer high two-dimensional electron gas (2DEG) concentration, high switching speed, high critical electric field, and good thermal properties, and have the potential to bring a breakthrough in the power rectifier market. Conventional AlGaN/GaN planar SBDs (conv.-SBDs) exhibit an undesired high onset voltage (V on ), 12,13) leading to a considerable conduction loss.…”