Selective Area Regrowth Produces Nonuniform Mg Doping Profiles in Nonplanar GaN p-n Junctions

Alexander S. Chang, Bingjun Li, Sizhen Wang, Mohsen Nami, Paul J.M. Smeets, Jung Han, Lincoln J. Lauhon*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

3 Scopus citations

Abstract

Nonplanar GaN p-n junctions formed by selective area regrowth were analyzed using pulsed laser atom probe tomography. Dilute Al marker layers were used to map the evolution of the p-GaN growth interface, enabling extraction of time-varying growth rates for nonpolar, semipolar, and polar surfaces from the trench edge to the center, respectively. The Mg dopant concentration is facet-dependent and varies inversely with the growth rate for the semipolar facets that grow rapidly away from the trench sidewalls. The negligible growth on the vertical sidewall of the trench coincides with an order of magnitude higher Mg concentration and substantial clustering of likely inactive dopants. A high Mg concentration is also observed near the regrowth interface of polar and semipolar planes, which we attribute to etching damage. We conclude that device fabrication processes employing selective area regrowth on nonplanar interfaces should consider both the spatial and temporal dependencies of growth rate that lead to nonuniform doping and explore growth conditions that could reduce variations in growth rate when nonuniform doping would adversely affect device performance.

Original languageEnglish (US)
Pages (from-to)704-710
Number of pages7
JournalACS Applied Electronic Materials
Volume3
Issue number2
DOIs
StatePublished - Feb 23 2021

Keywords

  • atom probe tomography
  • dopant profiling
  • gallium nitride
  • p-n junction
  • selective area doping
  • selective area regrowth

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Electrochemistry
  • Materials Chemistry

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