Design space and origin of off-state leakage in GaN vertical power diodes

Abstract

Variable-range-hopping through disl identified as the main off-state leakage m GaN vertical diodes on different substrates. of leakage current for vertical devices as dislocation density and electric field was der simulations, after careful calibration with ex literature data. Designed GaN vertical diode 2-4 orders of magnitude lower leakage supporting 3-5 times higher electric field, GaN lateral, Si and SiC devices.

GaN-on-Si Quasi-Vertical Power MOSFETs

“…4 (b), indicates that the device leakage current mainly flows through the heterostructure, instead of the etched sidewalls [30]. The relation between leakage current density (I) and the average electric field (E) in the drift layer reveals the off-state leakage mechanism [36]. The nearly linear dependence of ln(I)∝E (extracted from Fig.…”

Lateral Charge Transport in the Carbon-Doped Buffer in AlGaN/GaN-on-Si HEMTs

“…It is now well known that leakage in GaN P-N diodes occurs along dislocations with high screw component [32] and here we assume that a small proportion of those paths dominates the leakage. These randomly separated discrete leakage paths with separation ~100µm would provide a source of electrons which could neutralize the spreading 2DHG and pin its potential closer to the Si substrate as shown schematically in Fig.…”

Materials and processing issues in vertical GaN power electronics

“…To understand the full potential of vertical GaN-on Si devices, it is important to study the origin and design space of the off-state leakage current [68]. This leakage is dominated by the variable-range hopping through threading dislocations and the device breakdown is typically given by trap-assisted space-charge limited current [68]. In comparison, vertical GaN-on-GaN pn diodes have similar leakage mechanisms but show avalanche breakdown.…”

“…In Ref. [68], the MIT group and Synopsys demonstrated a simulation model for the leakage current in vertical GaN power devices, with the simulation model well calibrated by the experimental data of vertical GaN power diodes on Si, sapphire and GaN substrates. From the simulation, they derived the design space of leakage current of vertical GaN power devices (Fig.…”

“…Design space of the off-state leakage current of vertical GaN diodes as a function of the total dislocation density level in the structure, and the average electric field in the drift layer (E AV = 13 MV/cm).The different dislocation density represents vertical GaN diodes fabricated on different substrates. The leakage currents of state-of-the-art GaN lateral diodes with similar Eav and dislocation density are also shown[68].…”