Introduction and recovery of Ga and N sublattice defects in electron-irradiated GaN

Journal Article · Mon Oct 15 00:00:00 EDT 2007 · Physical Review. B, Condensed Matter and Materials Physics

DOI:https://doi.org/10.1103/PHYSREVB.76.165207· OSTI ID:21052731

Tuomisto, F; Ranki, V; Look, D C; Farlow, G C ^[1]

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1. Laboratory of Physics, Helsinki University of Technology, P.O. Box 1100, 02015 TKK (Finland)

We have used positron annihilation spectroscopy to study the introduction and recovery of point defects introduced by 0.45 and 2 MeV electron irradiation at room temperature in n-type GaN. Isochronal annealings were performed up to 1220 K. We observe vacancy defects with specific lifetime of {tau}{sub V}=190{+-}15 ps that we tentatively identify as N vacancies or related complexes in the neutral charge state in the samples irradiated with 0.45 MeV electrons. The N vacancies are produced at a rate {sigma}{sub N}{sup 0.45}{approx_equal}0.25 cm{sup -1}. The irradiation with 2 MeV electrons produces negatively charged Ga vacancies and negative nonopen volume defects (negative ions) originating from the Ga sublattice, at a rate {sigma}{sub Ga}{sup 2.0}{approx_equal}5 cm{sup -1}. The irradiation-induced N vacancies anneal out of the samples at around 600 K, possibly due to the motion of the irradiation-induced N interstitials. Half of the irradiation-induced Ga vacancies anneal out of the samples also around 600 K, and this is interpreted as the isolated Ga vacancies becoming mobile with a migration barrier of E{sub M}{sup V,Ga}=1.8{+-}0.1 eV. Interestingly, we observe a change of charge state of the irradiation-induced negative ions from 2- to 1- likely due to a reconstruction of the defects in two stages at annealing temperatures of about 600 and 700 K. The negative ions anneal out of the samples together with the other half of the Ga vacancies (stabilized by, e.g., N vacancies and/or hydrogen) in thermal annealings at 800-1100 K.

• OSTI ID: 21052731
• Journal Information: Physical Review. B, Condensed Matter and Materials Physics, Vol. 76, Issue 16; Other Information: DOI: 10.1103/PhysRevB.76.165207; (c) 2007 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA); ISSN 1098-0121
• Country of Publication: United States
• Language: English

Related Subjects

75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ANIONS
ANNEALING
ANNIHILATION
CHARGE STATES
CRYSTALS
DEFECTS
ELECTRON BEAMS
ELECTRONS
EV RANGE
GALLIUM NITRIDES
HYDROGEN
INTERSTITIALS
IRRADIATION
MEV RANGE 01-10
POSITRONS
SEMICONDUCTOR MATERIALS
SPECTROSCOPY
TEMPERATURE RANGE
VACANCIES