5.0 kV breakdown-voltage vertical GaN p–n junction diodes

Abstract

A high breakdown voltage of 5.0 kV has been achieved for the first time in vertical GaN p-n junction diodes by using our newly developed guardring structures. A resistance device was inserted between the main diode portion and the guard-ring portion in a ring-shaped p-n diode to generate a voltage drop over the resistance device by leakage current flowing through the guard-ring portion under negatively biased conditions before breakdown. The voltage at the outer mesa edge of the guard-ring portion, where the electric field intensity is highest and the destructive breakdown usually occurs, is decreased by the voltage drop, so the electric field concentration in the portion is reduced. By adopting this structure, the breakdown voltage (V B ) is raised by about 200 V. Combined with a low measured on-resistance (R on ) of 1.25 mΩ cm 2 , Baliga's figure of merit ðV 2 B =R on Þ was as high as 20 GW/cm 2 .

High voltage GaN p‐n diodes formed by selective area regrowth

“…This result corroborates the ability of AZ400K to mitigate ICP-induced etch damage [11]. However, the etched-and-regrown diode electrical performance significantly lags that of continuously-grown GaN diodes [2][3][4][5][6], which could be due to substrate effects, lack of JTE, Si incorporation during regrowth, or combinations thereof. While etched-and-regrown GaN diode performance lagged that of continuously-grown GaN diodes, they greatly exceeded the Si unipolar limit.…”

“…The rapid development of GaN substrates has stoked interest in GaN power diodes [2][3][4][5][6] because of their potential to outperform SiC devices owing to the higher μ and larger E crit for GaN. Moving GaN beyond diodes to merged p-i-n Schottky (MPS) devices or junction field-effect transistors (JFETs) will require selective area p-type doping, but this has been difficult to achieve.…”

Structural and Electrical Characterization of 2” Ammonothermal Free-Standing GaN Wafers. Progress toward Pilot Production

“…In addition to having a low dislocation density, growing GaN devices on GaN substrates (GaN-on-GaN) allows vertical device architectures which have better thermal management, higher reliability, and high breakdown voltages using small devices as compared to lateral devices [10]. Recent research on high-power vertical devices on bulk GaN can be found in references [11,12,13,14,15,16]. It has also been shown that GaN-on-GaN LEDs can operate efficiently at high current density unlike heteroepitaxial LEDs which experience a strong efficiency droop as current density is increased [17].…”

Effect of Wafer Off‐Angles on Defect Formation in Drift Layers Grown on Free‐Standing GaN Substrates

“…Free‐standing GaN substrates allow epitaxial growth of a thick drift layer with low dislocation density. Compared with a p–n diode, a Schottky diode has the advantage of a lower turn‐on voltage . The key issue is to form thick, high‐quality n‐GaN layers with low carrier density for the drift layer.…”

“…Compared with a p-n diode, a Schottky diode has the advantage of a lower turn-on voltage. [11][12][13][14][15][16] The key issue is to form thick, high-quality n-GaN layers with low carrier density for the drift layer.…”