Comprehensive characterization of vertical GaN-on-GaN Schottky barrier diodes

Description

This paper reports comprehensive characterization of vertical GaN-on-GaN Schottky barrier diodes (SBDs) fabricated on free-standing GaN substrates. The GaN active layer properties are evaluated by atomic force microscopy (AFM), secondary-ion mass spectrometry (SIMS), micro-Raman spectroscopy, cathodoluminescence (CL), and deep-level transient Fourier spectroscopy (DLTFS). The GaN SBDs exhibit near-unity ideality factor (n = 1.1), promising Schottky barrier height (SBH) of ΦB = 0.82 eV, low turn-on voltage ~0.56 V, leakage current density of JR < 5.5×10-6 Acm-2 at-100 V, breakdown voltage VBR <-200 V, and less interface state density (NSS < 5×10 12 eV-1 cm-2) at the Ni/GaN Schottky contact. The forward and reverse current transport mechanisms of the SBD are identified by fitting analysis of measured J-V. Weak temperature dependence of ΦB and n is detected from I-V-T measurements. Similar traps at EC-0.18 eV and EC-0.56 are identified in the various SBDs from DLTFS, signifying that these traps are omnipresent defects in the epilayer.

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