Determination of electronic band structure by electron holography of etched-and-regrown interfaces in GaN p-i-n diodes

Shanthan R. Alugubelli, Houqiang Fu, Kai Fu, Hanxiao Liu, Yuji Zhao, Martha R. McCartney, Fernando A. Ponce

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Abstract

The electrostatic potential variation across etched-and-regrown GaN p-i-n diodes for power electronics has been studied using electron holography in a transmission electron microscope. The potential profiles have been correlated with the composition profiles of Mg, Si, and O obtained by secondary ion mass spectroscopy. Electronic charges obtained from the potential profiles correlate well with the presence of Si and O impurities at regrown interfaces. The overlap of Mg and Si when Mg doped GaN is grown directly over an etched undoped GaN surface results in the formation of a highly doped p-n junction. The introduction of a thin undoped layer over the etched GaN surface prevents the formation of such a junction as the regrowth interface is moved away from the Mg-doped GaN, and results in diodes with improved reverse leakage currents, close to the best values of continuously grown p-i-n diodes. Potential profiles of continuously grown (not etched) p-i-n diodes are compared to those of etched-and-regrown diodes.

Original languageEnglish (US)
Article number201602
JournalApplied Physics Letters
Volume115
Issue number20
DOIs
StatePublished - Nov 11 2019

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ASJC Scopus subject areas

  • Physics and Astronomy (miscellaneous)

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