Reverse Leakage Analysis for As-Grown and Regrown Vertical GaN-on-GaN Schottky Barrier Diodes

Abstract

Vertical GaN-on-GaN Schottky barrier diodes based on as-grown and regrown samples were fabricated to investigate the effects of the etch-then-regrow process on device performance. The surface roughness increased slightly after dry etching and decreased after regrowth. According to X-ray diffraction results, the etch-then-regrow process caused a slight increase of defect density due to increased edge dislocations. Schottky parameters extracted from forward current-voltage curves, such as turn-on voltages of 0.74 V and 0.72 V, ideality factors of 1.07 and 1.10, and barrier heights of 1.07 eV and 1.05 eV, were obtained for diodes based on the regrown and as-grown samples, respectively. The breakdown voltage of the regrown sample was much lower than the as-grown sample. The regrowth interface can be regarded as a n-doping GaN layer due to the high interface charge density after the etch-then-regrown process. This equivalent n-doping GaN layer reduced the effective thickness of the UID-GaN under the Schottky contact thus causing lower breakdown voltage for the regrown sample. Poole-Frenkel emission and trap-assisted tunneling processes were responsible for the leakage of both as-grown and regrown samples according to the temperature dependence of the reverse currents.INDEX TERMS Schottky barrier diodes, GaN-on-GaN, regrow, leakage, interface.

Low Leakage and High Forward Current Density Quasi-Vertical GaN Schottky Barrier Diode With Post-Mesa Nitridation

“…5(b), a temperature increasing from 25 • C to 150 • C results in an increase of leakage current density by about two orders of magnitude. According to the leakage mechanism reported [27], [32], [33], in the low reverse bias range (E av < 0.4 MV/cm), the leakage process might be dominated by the TE mechanism. The device leakage current is beyond the limit of measurement instrument (∼10 −14 A) (Agilent B1500A) at low temperature, thus deviating from the TE model.…”

Characterization of As-Grown and Regrown GaN-on-GaN Structures for Vertical p-n Power Devices

“…The high leakage current of these devices and their failure at low voltage (45-95V) can most likely be attributed to surface roughness induced by etching, which was revealed in a previous atomic-force microscopy study of similar as-grown and etched devices. 22 The etched area showed the segregation of precipitates near the interface, as well as the presence of silicon, oxygen and magnesium which were detected from SIMS analysis. 18 The Si presence could possibly be due to leftover residue in the MOCVD chamber which was deposited on the surface when the devices were reintroduced for p-GaN regrowth after etching treatments.…”

First Demonstration of L-Band High-Power Limiter with GaN Schottky Barrier Diodes (SBDs) Based on Steep-Mesa Technology

“…The GaN SBDs with various L AC showed a similar breakdown voltage (BV) of 106 V at 1 A/cm 2 and a similar leakage density of 10 −8 A/cm 2 until -30 V. L AC had minor impact on reverse BV, which can be explained by the electric field distributed mostly in the drift layer. When the reverse bias exceeded 30 V, the leakage behavior showed a variable range-hopping (VRH) process, which could be attributed to the threading dislocation in the bulk [21]. Figure 4b shows the temperature-dependent I-V characteristics of the SBDs, which ranged between 300 and 425 K. With increasing temperature, the current density increased from 300 K (room temperature) to 425 K when the forward voltage was below 1 V, which was attributed to the thermionic emission (TE) behavior.…”