Thermoelectric properties of epitaxial ScN films deposited by reactive magnetron sputtering onto MgO(001) substrates

Journal Article · Sun Apr 21 00:00:00 EDT 2013 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.4801886· OSTI ID:22102356

Burmistrova, Polina V.; Rui Koh, Yee; Lundstrom, Mark S. ^[1]; Maassen, Jesse; Salamat, Shuaib ^[1]; Favaloro, Tela ^[2]; Saha, Bivas ^[3]; Shakouri, Ali ^[1]; Sands, Timothy D. ^[1]

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1. School of Electrical and Computer Engineering, Purdue University, West Lafayette, Indiana 47907 (United States)
2. School of Engineering, University of California Santa Cruz, Santa Cruz, California 95064 (United States)
3. Birck Nanotechnology Center, Purdue University, West Lafayette, Indiana 47907 (United States)

Epitaxial ScN(001) thin films were grown on MgO(001) substrates by dc reactive magnetron sputtering. The deposition was performed in an Ar/N{sub 2} atmosphere at 2 Multiplication-Sign 10{sup -3} Torr at a substrate temperature of 850 Degree-Sign C in a high vacuum chamber with a base pressure of 10{sup -8} Torr. In spite of oxygen contamination of 1.6 {+-} 1 at. %, the electrical resistivity, electron mobility, and carrier concentration obtained from a typical film grown under these conditions by room temperature Hall measurements are 0.22 m{Omega} cm, 106 cm{sup 2} V{sup -1} s{sup -1}, and 2.5 Multiplication-Sign 10{sup 20} cm{sup -3}, respectively. These films exhibit remarkable thermoelectric power factors of 3.3-3.5 Multiplication-Sign 10{sup -3} W/mK{sup 2} in the temperature range of 600 K to 840 K. The cross-plane thermal conductivity is 8.3 W/mK at 800 K yielding an estimated ZT of 0.3. Theoretical modeling of the thermoelectric properties of ScN calculated using a mean-free-path of 23 nm at 300 K is in very good agreement with the experiment. These results also demonstrate that further optimization of the power factor of ScN is possible. First-principles density functional theory combined with the site occupancy disorder technique was used to investigate the effect of oxygen contamination on the electronic structure and thermoelectric properties of ScN. The computational results suggest that oxygen atoms in ScN mix uniformly on the N site forming a homogeneous solid solution alloy. Behaving as an n-type donor, oxygen causes a shift of the Fermi level in ScN into the conduction band without altering the band structure and the density of states.

• OSTI ID: 22102356
• Journal Information: Journal of Applied Physics, Vol. 113, Issue 15; Other Information: (c) 2013 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
36 MATERIALS SCIENCE
CARRIER DENSITY
CARRIERS
DENSITY FUNCTIONAL METHOD
ELECTRIC CONDUCTIVITY
ELECTRON MOBILITY
ELECTRONIC STRUCTURE
EPITAXY
FERMI LEVEL
LAYERS
MAGNESIUM OXIDES
MEAN FREE PATH
SCANDIUM NITRIDES
SEMICONDUCTOR MATERIALS
SIMULATION
SOLID SOLUTIONS
SUBSTRATES
THERMAL CONDUCTIVITY
THERMOELECTRIC PROPERTIES
THIN FILMS