High-quality Thin Single Crystal Sc2O3 Films Grown on Si (111)
C. P. Chen (陳治平)1, M. Hong (洪銘輝)1, A. R. Kortan1, P. Chang (張翔筆)1,
Y. L. Huang (黃怡霖)1, H. Y. Lee (李信義)2, J. Kwo (郭瑞年)3, M. W. Chu (朱明文)4,
C. H. Chen (陳正弦)4, L. Goncharova5, E. Garfunkel5, and T. Gustafsson5
1
Department of Materials Science and Engineering, Tsing Hua University, Hsinchu, Taiwan
2
National Synchrotron Radiation Research Center, Hsinchu, Taiwan
3
Department of Physics, Tsing Hua University, Hsinchu, Taiwan
4
Center for Condensed Matter Sciences, Taiwan University, Taipei, Taiwan
5
Departments of Physics and Chemistry, Rutgers University, Piscataway, USA
Sc2O3 has recently gained attention due to its effective passivation on GaN, and its usage as a
gate dielectric in GaN based MOS devices. Sc2O3 is also attractive as an alternative gate dielectric
for Si due to its relatively high dielectric constant of ~14, large bandgap of ~ 6 eV, and
thermodynamic stability with Si. When the oxide layer thickness approaches a few atomic layers,
the dielectric uniformity may be best supported by epitaxial single crystalline oxide films. Sc2O3
thin films were found unexpectedly to grow epitaxially on Si (111)1,2 and sapphire3 with excellent
crystal quality.
Single-crystal Sc2O3 films of a few nanometer thick have been epitaxially grown on Si (111)
substrates despite a huge lattice mismatch. The oxide films were electron beam evaporated from a
high-purity powder-packed Sc2O3 target. The structural and morphological studies carried out by
x-ray diffraction in a synchrotron radiation source, XRR, AFM, HR-TEM, and MEIS, with the
initial epitaxial growth monitored by in-situ RHEED. The oxide films have the cubic bixbyite phase
with a remarkably uniform thickness and high structural perfection. The film surfaces are very
smooth and the oxide/Si interfaces are atomically sharp. The Sc2O3 films are well aligned with the
Si substrate with an orientation relationship of Si (111) // Sc2O3 (111), and an in-plane expitaxy of
Si [ 1 10 ] // Sc2O3 [ 1 01 ].
References
[1]. C. P. Chen, M. Hong, J. Kwo, H. M. Cheng, Y. L. Huang, S. Y. Lin, J. Chi, H. Y. Lee, Y. F.
Hsieh, and J. P. Mannaerts, J. Crystal Growth, 278, 638 (2005).
[2]. D. O. Klenov, L. F. Edge, D. G. Schlom, and S. Stemmer, Appl. Phys. Lett. 86, 051901 (2005).
[3]. A. R. Kortan, M. Hong, J. Kwo, P. Chang, C. P. Chen, J. P. Mannaerts, and S. H. Liou, Mat. Res.
Soc. Symp. Proc. 811, p. E1.2, (2004)