Production of Native Donors in ZnO by Annealing at High Temperature in Zn Vapor

Journal Article · Sat Jan 01 04:00:00 UTC 2005 · Applied Physics Letters

DOI:https://doi.org/10.1063/1.2117630· OSTI ID:1003063

Halliburton, L. E. ^[1]; Giles, N. C. ^[1]; Garces, N. Y. ^[2]; Luo, Ming ^[1]; Xu, Chunchuan ^[1]; Bai, Lihai ^[3]; Boatner, Lynn A ^[4]

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1. West Virginia University
2. Naval Research Laboratory, Washington, D.C.
3. Fisk University, Nashville, TN
4. ORNL

Zinc oxide crystals grown by the seeded chemical vapor transport method have been annealed in zinc vapor at 1100 {sup o}C for 30 min. These thermochemical reduction treatments produce a deep red coloration in the crystals and increase their n-type electrical conductivity. Electron paramagnetic resonance (EPR), optical absorption, and Hall measurements were used to monitor changes in the crystals. After an anneal, an intense optical absorption band is present that extends from the band edge out to approximately 550 nm, and the EPR signal near g = 1.96 (due to shallow donors and/or conduction-band electrons), the free-carrier absorption, and the Hall electron concentration are all larger. Hydrogen was not present during these anneals, thus leaving oxygen vacancies and zinc interstitials as candidates for the added donors. Neutral oxygen vacancies are produced at high temperature by the additive-coloration mechanism, and are responsible for the broad near-edge absorption band. The observed increase in the number of free carriers is a result of either (1) the formation of zinc interstitials or (2) having the ground state of the neutral oxygen vacancy near the conduction band.

• Research Organization: Oak Ridge National Laboratory (ORNL)
• Sponsoring Organization: SC USDOE - Office of Science (SC)
• DOE Contract Number: AC05-00OR22725
• OSTI ID: 1003063
• Journal Information: Applied Physics Letters, Journal Name: Applied Physics Letters Journal Issue: 17 Vol. 87; ISSN 0003-6951
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ABSORPTION
ANNEALING
CARRIER DENSITY
CHEMICAL VAPOR DEPOSITION
CRYSTAL GROWTH
CRYSTALS
ELECTRIC CONDUCTIVITY
ELECTRON SPIN RESONANCE
GROUND STATES
HALL EFFECT
OXYGEN
PRODUCTION
TEMPERATURE RANGE 0400-1000 K
VAPORS
VISIBLE SPECTRA
ZINC
ZINC COMPOUNDS
ZINC OXIDES