Interfacial $\mathrm{N}$ Vacancies in $\mathrm{Ga}\mathrm{N}$/($\mathrm{Al}$,$\mathrm{Ga}$)$\mathrm{N}$/$\mathrm{Ga}\mathrm{N}$ Heterostructures

Interfacial $N$ Vacancies in $Ga N$ /( $Al$ , $Ga$ ) $N$ / $Ga N$ Heterostructures

Vera Prozheeva, Ilja Makkonen, Haoran Li, Stacia Keller, Umesh K. Mishra, and Filip Tuomisto

Phys. Rev. Applied 13, 044034 – Published 13 April 2020

Abstract

We show that $N$ -polar $Ga N$ / $(Al, Ga) N$ / $Ga N$ heterostructures exhibit significant $N$ deficiency at the bottom $(Al, Ga) N$ / $Ga N$ interface, and that these $N$ vacancies are responsible for the trapping of holes observed in unoptimized $N$ -polar $Ga N$ / $(Al, Ga) N$ / $Ga N$ high electron mobility transistors. We arrive at this conclusion by performing positron annihilation experiments on $Ga N$ / $(Al, Ga) N$ / $Ga N$ heterostructures of both $N$ and $Ga$ polarity, as well as state-of-the-art theoretical calculations of the positron states and positron-electron annihilation signals. We suggest that the occurrence of high interfacial $N$ vacancy concentrations is a universal property of nitride semiconductor heterostructures at net negative polarization interfaces.

Received 16 October 2019
Revised 7 January 2020
Accepted 24 March 2020

DOI:https://doi.org/10.1103/PhysRevApplied.13.044034

Physics Subject Headings (PhySH)

Vacancies

Field-effect transistors Heterostructures III-V semiconductors Nitrides Solid-solid interfaces Two-dimensional electron gas

Positron annihilation spectroscopy

Accelerators & BeamsCondensed Matter, Materials & Applied Physics

Authors & Affiliations

Vera Prozheeva¹, Ilja Makkonen ², Haoran Li³, Stacia Keller ³, Umesh K. Mishra³, and Filip Tuomisto ^1,2,*

¹Department of Applied Physics, Aalto University, P.O. Box 15100, FI-00076 Aalto, Finland
²Department of Physics and Helsinki Institute of Physics, University of Helsinki, P.O. Box 43, FI-00014 Helsinki, Finland
³Electrical and Computer Engineering Department, University of California, Santa Barbara, California, USA