Barrier Inhomogeneity of Schottky Diode on Nonpolar AlN Grown by Physical Vapor Transport

Qin Zhou,Yan Lin,Honglei Wu,Dan Dong,Baikui Li,Hui Li,Xi Tang,Jiannong Wang,Chengjin Lu,Zuoyan Qin,Ran Qiu,Ruisheng Zheng

doi:10.1109/jeds.2019.2923204

Abstract

An aluminum nitride (AlN) Schottky barrier diode (SBD) was fabricated on a nonpolar AlN crystal grown on tungsten substrate by physical vapor transport. The Ni/Au-AlN SBD features a low ideality factor n of 3.3 and an effective Schottky barrier height (SBH) of 1.05 eV at room temperature. The ideality factor n decreases and the effective SBH increases at high temperatures. The temperature dependences of n and SBH were explained using an inhomogeneous model. A mean SBH of 2.105 eV was obtained for the Ni-AlN Schottky junction from the inhomogeneity analysis of the current-voltage characteristics. An equation in which the parameters have explicit physical meanings in thermionic emission theory is proposed to describe the current-voltage characteristics of inhomogeneous SBDs.

Highlights

Aluminum nitride (AlN), with a bandgap energy of 6.1 eV and a critical electric field of up to 12 MV/cm, possesses great potential in power electronics and deep UV optoelectronics [1]–[3]
Though reported almost a century earlier [4] than its counterpart, gallium nitride (GaN) [5], which has been the main force of power electronics [6], [7] and optoelectronics [8], [9], high-quality AlN crystals and epilayers had not been achieved until recently [10]–[15]
Schottky barrier diodes (SBDs) on AlN grown by physical vapor transport (PVT) [17], by hydride vapor phase epitaxy (HVPE) [18], and by metal organic chemical vapor deposition (MOCVD) [19] have been reported

Summary

INTRODUCTION

Aluminum nitride (AlN), with a bandgap energy of 6.1 eV and a critical electric field of up to 12 MV/cm, possesses great potential in power electronics and deep UV optoelectronics [1]–[3]. The temperature dependences of the ideality factor n and the effective SBH extracted from the J–V curves were explained using an inhomogeneous model [22], [30]–[33]. Taking the value of A* to be ∼57.6 A/(cm2K2) for AlN [18], the ideality factor n and SBH of the Ni/AlN SBD at 300 K were extracted to be 3.3 and 1.05 eV, respectively, from the linear segment of the ln(J)-V curve. KT including proper passivation and field-plate design should be introduced to enhance the reverse bias blocking capability

JUNCTION INHOMOGENEITY ANALYSIS

DISCUSSIONS