Comprehensive characterization of vertical GaN-on-GaN Schottky barrier diodes. (October 2022) - Raja, P. Vigneshwara
Abstract: 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 Φ B = 0.82 eV, low turn-on voltage ∼0.56 V, leakage current density of J R < 5.5 × 10 −6 Acm −2 at −100 V, breakdown voltage V BR < −200 V, and less interface state density ( N SS < 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 Φ B 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. Highlights: Comprehensive characterizations are carried out for vertical GaN-on-GaN Schottky barrier diodes (SBDs). Typical electrical characteristics of quasi-ideal vertical GaN-on-GaN SBDs are reported. Various current transport mechanisms involved during forward and reverse characteristics of the SBD are identified. The GaN active layer properties are evaluated by AFM, SIMS, micro-Raman spectroscopy, cathodoluminescence (CL). Furthermore, traps in the GaN diodes are detected by deep level transient Fourier spectroscopy (DLTFS).