Design and development of 1.5 kV vertical GaN pn diodes on HVPE substrate

Abstract

We report the design and development of vertical 1.5 kV GaN p-n diodes that consists of an 8 μm drift layer and a thin p-GaN/p + -GaN layer grown by metal-organic chemical vapor deposition (MOCVD) on a hydride vapor phase epitaxy (HVPE) synthesized GaN substrate. The drift layer has a low doping concentration of ∼9 × 10 15 cm −3 and electron mobility ~ 1200 cm 2 /Vs at room temperature. The fabricated devices with an optimized guard ring design as edge termination exhibit a breakdown voltage of > 1.5 kV with specific on-resistance of ~ 1.5 mΩ cm 2 . The breakdown efficiency of these diodes is over 72% when compared to ideal analytical calculations and over 90% with respect to numerical simulations. Temperature-dependent measurements show that the devices have a positive temperature coefficient suggesting the avalanche breakdown mechanism. These results suggest that these MOCVD grown vertical GaN-on-GaN (HVPE) p-n diodes are promising for low-mid range voltage power switching applications.

GaN Power p–n Diodes on Hydride Vapor Epitaxy GaN Substrates with Near‐Unity Ideality Factor and <0.5 mΩ cm2Specific On‐Resistance

“…If approaches such as junction edge termination, passivation, and field plate for electrical field profile management are implemented, a significantly higher breakdown voltage can be expected. [33,34] Apart from being able to achieve fairly uniform breakdown, the fact that the devices have low specific on-resistance and near-unity ideality factor has higher impact. Both these device characteristics depict not only the higher material quality but also better switching performance.…”

Prospective view of nitride material synthesis

“…[4][5][6][7] As single crystals, many of the nitrides have favorable properties for opto-electronic use, including (ultra-)wide band gaps 8,9 and high reverse bias diode breakdown voltages. 10,11 Many of the covalent nitrides (especially Group III nitrides like BN, AlN, GaN, InN) offer particular advantages over other electronic material candidates such as silicon, GaAs and carbides like SiC. In Figure 1, these materials are compared based on their operating frequency versus power carrying capacity.…”