GaN Power Schottky Diodes with Drift Layers Grown on Four Substrates

Autor: Kenneth A. Jones, Joshua R. Smith, Edward A. Preble, Randy P. Tompkins, K. Udwary, Fatemeh Shahedipour-Sandvik, Puneet Suvarna, Jacob H. Leach, K.W. Kirchner, Jeffrey M. Leathersich
Rok vydání: 2014
Předmět:
Zdroj: Journal of Electronic Materials. 43:850-856
ISSN: 1543-186X
0361-5235
Popis: We have examined the performance of gallium nitride (GaN) high-power Schottky diodes fabricated on unintentionally doped (UID) metalorganic chemical vapor deposition (MOCVD) films grown simultaneously on four substrates ranging in threading dislocation density from 5 × 103 cm - 2 to 1010 cm - 2. The substrates were an intentionally doped and a UID freestanding hydride vapor phase epitaxy substrate, an MOCVD GaN template grown on a sapphire wafer, and a bulk GaN substrate grown via an ammonothermal method. Capacitance–voltage (C–V) results showed the carrier concentration was ∼2 × 1016 cm−3 for films grown on each of the four substrates. With that doping level, the theoretical breakdown voltage (Vb) is ∼1600 V. However, measured Vb for the devices tested on each of the four substrates fell short of this value. Also, the breakdown voltages across each of the four substrates were not substantially different. This result was especially surprising for films grown on bulk GaN substrates, because of their superior crystal quality, as determined from their x-ray rocking curve widths. Simple probability calculations showed that most of the diodes tested on the bulk substrate did not cover a single threading dislocation. Although optimization of edge-termination schemes is likely to improve Vb, we believe that point defects, not threading dislocations, are the main reason for the reduced performance of these devices.
Databáze: OpenAIRE
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