Abstract
Four epitaxial ScN(001) thin films were successfully deposited on MgO(001) substrates by dc reactive magnetron sputtering at 2, 5, 10, and 20 mTorr in an Ar/N2 ambient atmosphere at 650 °C. The microstructure of the resultant films was analyzed by x-ray diffraction, scanning electron microscopy, and transmission electron microscopy. Electrical resistivity, electron mobility and concentration were measured using the room temperature Hall technique, and temperature dependent in-plain measurements of the thermoelectric properties of the ScN thin films were performed. The surface morphology and film crystallinity significantly degrade with increasing deposition pressure. The ScN thin film deposited at 20 mTorr exhibits the presence of <221> oriented secondary grains resulting in decreased electric properties and a low thermoelectric power factor of 0.5 W/mK2 at 800 K. The ScN thin films grown at 5 and 10 mTorr are single crystalline, yielding the power factor of approximately 2.5 W/mK2 at 800 K. The deposition performed at 2 mTorr produces the highest quality ScN thin film with the electron mobility of 98 cm2 V−1 s−1 and the power factor of 3.3 W/mK2 at 800 K.
Similar content being viewed by others
References
K.A. Gschneider, G.A. Melson, D.A. Melson, D.H. Youngblood, and H.H. Schock: Scandium: Its Occurrence (Academic Press, London, 1975), p. 165.
D. Gall, I. Petrov, L.D. Madsen, J-E. Sundgren, and J.E. Greene: Microstructure and electronic properties of the refractory semiconductor ScN grown on MgO(001) by ultra-high vacuum reactive magnetron sputter deposition. J. Vac. Sci. Technol., A 16, 2411 (1998).
D. Gall, M. Stadele, K. Jarrendahl, I. Petrov, P. Desjardins, R.T. Haasch, T-Y. Lee, and J.E. Greene: Electronic structure of ScN determined using optical spectroscopy, photoemission, and ab initio calculations. Phys. Rev. B 63, 125119 (2001).
D. Gall, I. Petrov, N. Hellgren, L. Hultman, J.E. Sundgren, and J.E. Greene: Growth of poly- and single-crystal ScN on MgO(001): Role of low-energy N2+ irradiation in determining texture, microstructure evolution, and mechanical properties. J. Appl. Phys. 84, 6034 (1998).
B. Saha, J. Acharya, T.D. Sands, and U.V. Waghmare: Electronic structure, phonons, and thermal properties of ScN, ZrN, and HfN: A first-principles study. J. Appl. Phys. 107, 033715 (2010).
M.A. Moram, Z.H. Barber, and C.J. Humphreys: The effect of oxygen incorporation in sputtered scandium nitride films. Thin Solid Films 516, 8569 (2008).
J.P. Dismukes, W.M. Yim, and V.S. Ban: Epitaxial growth and properties of semiconducting ScN. J. Cryst. Growth 13, 365 (1972).
J.M. Gregoire, S.D. Kirby, G.E. Scopelianos, F.H. Lee, and R.B. van Dover: High mobility single crystalline ScN and single-orientation epitaxial YN on sapphire via magnetron sputtering. J. Appl. Phys. 104, 074913 (2008).
J.M. Gregoire, S.D. Kirby, M.E. Turk, and R.B. van Dover: Structural, electronic and optical properties of (Sc, Y) N solid solutions. Thin Solid Films 517, 1607 (2009).
P.V. Burmistrova, J. Maassen, T. Favaloro, B. Saha, S. Salamat, Y.R. Koh, K.S. Lundstrom, A. Shakouri, and T.D. Sands: Thermoelectric properties of epitaxial ScN films deposited by reactive magnetron sputtering onto MgO(100) substrates. J. Appl. Phys. 113, 153704 (2013).
S. Kerdsongpanya, N. van Nong, N. Pryds, A. Zukauskaite, J. Jensen, J. Birch, J. Lu, L. Hultman, G. Wingqvist, and P. Eklund: Anomalously high thermoelectric power factor in epitaxial ScN thin films. Appl. Phys. Lett. 99, 232113 (2011).
M.A. Moram, S.V. Novikov, A.J. Kent, C. Nörenberg, C.T. Foxon, and C.J. Humphreys: Growth of epitaxial thin films of scandium nitride on 100-oriented silicon. J. Cryst. Growth 310, 2746 (2008).
S.W. King, R.F. Davis, and R.J. Nemanich: Gas source molecular beam epitaxy of scandium nitride on silicon carbide and gallium nitride surfaces. J. Vac. Sci. Technol., A 32, 061504 (2014).
S.W. King, R.J. Nemanich, and R.J. Davis: Valence and conduction band alignment at ScN interfaces with 3C-SiC (111) and 2H-GaN (0001). Appl. Phys. Lett. 105, 081606 (2014).
Y. Oshima, E.G. Villora, and K. Shimamura: Hydride vapor phase epitaxy and characterization of high-quality ScN epilayers. J. Appl. Phys. 115, 153508 (2014).
S. Kerdsongpanya, B. Alling, and P. Eklund: Effect of point defects on the electronic density of states of ScN studied by first-principles calculations and implications for thermoelectric properties. Phys. Rev. B 86, 195140 (2012).
M.A. Moram, T.B. Joyce, P.R. Chalker, Z.H. Barber, and C.J. Humphreys: Microstructure of epitaxial scandium nitride films grown on silicon. Appl. Surf. Sci. 252, 8385 (2006).
M.A. Moram, M.J. Kappers, and C.J. Humphreys: Low dislocation density nonpolar (11–20) GaN films achieved using scandium nitride interlayers. Phys. Status Solidi C 7, 1778 (2010).
M.A. Moram, Y. Zhang, M.J. Kappers, Z.H. Barber, and C.J. Humphreys: Dislocation reduction in gallium nitride films using scandium nitride interlayers. Appl. Phys. Lett. 91, 152101 (2007).
M. Zebarjadi, Z. Bian, R. Singh, A. Shakouri, R. Wortman, V. Rawat, and T. Sands: Thermoelectric transport in a ZrN/ScN superlattice. J. Electron. Mater. 38, 960 (2009).
V. Rawat and T.D. Sands: Growth of TiN/GaN metal/semiconductor multilayers by reactive pulsed laser deposition. J. Appl. Phys. 100, 064901 (2006).
V. Rawat, Y.K. Koh, D.G. Cahill, and T.D. Sands: Thermal conductivity of (Zr,W)N/ScN metal/semiconductor multilayers and superlattices. J. Appl. Phys. 105, 024909 (2009).
S. Kerdsongpanya, B. Alling, and P. Eklund: Phase stability of ScN-based solid solutions for thermoelectric applications from first-principles calculations. J. Appl. Phys. 114, 073512 (2013).
R. Deng, S.R. Evans, and D. Gall: Bandgap in Al1−xScxN. Appl. Phys. Lett. 102, 112103 (2013).
C. Hoglund, J. Bareno, J. Birch, B. Alling, Z. Czigany, and L. Hultman: Cubic Sc1−xAlxN solid solution thin films deposited by reactive magnetron sputter epitaxy onto ScN(111). J. Appl. Phys. 105, 113517 (2009).
C. Hoglund, J. Birch, B. Alling, J. Bareno, Z. Czigany, P.O.A. Persson, G. Wingqvist, A. Zukauskaite, and L. Hultman: Increased electromechanical coupling in w-ScxAl1−xN. J. Appl. Phys. 107, 1235515 (2010).
M.A. Moram and S. Zhang: ScGaN and ScAlN: Emerging nitride materials. J. Mater. Chem. A 17, 6042 (2014).
P.V. Burmistrova: Microstructure and thermoelectric properties of ScN thin films and metal/ScN superlattices for high-temperature energy conversion. Ph.D. Dissertation, Purdue University, West Lafayette, 2014.
D. Gall, I. Petrov, P. Desjardins, and J.E. Greene: Microstructural evolution and Poisson ratio of epitaxial ScN grown on TiN(001)/MgO(001) by ultra-high vacuum reactive magnetron sputter deposition. J. Appl. Phys. 86, 5524 (1999).
J.A. Stroscio, D.T. Pierce, M.D. Stiles, A. Zangwill, and L.M. Sander: Coarsening of unstable surface features during Fe (001) homoepitaxy. Phys. Rev. Lett. 75, 4246 (1995).
B.W. Karr, I. Petrov, D.G. Cahill, and J.E. Greene: Morphology of epitaxial TiN(001) grown by magnetron sputtering. Appl. Phys. Lett. 70, 1703 (1997).
N.E. Lee, D.G. Cahill, and J.E. Greene: Evolution of surface roughness in epitaxial Si0.7Ge0.3(001) as a function of growth temperature (200-600°C) and Si(001) substrate miscut. J. Appl. Phys. 80, 2199 (1996).
G. Ehrlich and F.G. Hudda: Atomic view of surface self-diffusion: Tungsten on tungsten. J. Chem. Phys. 44, 1039 (1966).
S.C. Wang and G. Ehrlich: Adatom motion to lattice steps: A direct view. Phys. Rev. Lett. 70, 41 (1993).
A. Golzhauser and G. Ehrlich: Atom movement and binding on surface clusters: Pt on Pt(111) clusters. Phys. Rev. Lett. 77, 1334 (1996).
F.F. Leal, S.C. Ferreira, and S.O. Ferreira: Modelling of epitaxial film growth with an Ehrlich-Schwoebel barrier dependent on the step height. J. Phys.: Condens. Matter 23, 292201 (2011).
E. Burstein: Anomalous optical absorption limit in InSb. Phys. Rev. 93, 632 (1954).
ACKNOWLEDGMENTS
This work was funded by DARPA/Army Research Office Contract No. W911NF0810347. Research carried out in part at the Center for Functional Nanomaterials, Brookhaven National Laboratory, which is supported by the U.S. Department of Energy, Office of Basic Energy Sciences, under Contract No. DE-AC02-98CH10886.
Author information
Authors and Affiliations
Corresponding author
Additional information
This author was an editor of this journal during the review and decision stage. For the JMR policy on review and publication of manuscripts authored by editors, please refer to http://www.mrs.org/jmr-editor-manuscripts/
Rights and permissions
About this article
Cite this article
Burmistrova, P.V., Zakharov, D.N., Favaloro, T. et al. Effect of deposition pressure on the microstructure and thermoelectric properties of epitaxial ScN(001) thin films sputtered onto MgO(001) substrates. Journal of Materials Research 30, 626–634 (2015). https://doi.org/10.1557/jmr.2015.30
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1557/jmr.2015.30