Growth and Properties of Gadolinium Oxide Dielectric Layers on Silicon Carbide for High-K Application
We investigated the growth, interface formation as well as the structural and electrical properties of crystalline gadolinium oxide (Gd2O3) directly grown on 6H-SiC(0001) substrates by molecular beam epitaxy. The Gd2O3 layers were found to grow epitaxially resulting in the formation of flat (111) oriented layers with the cubic bixbyite type of structure. X-ray photoelectron spectroscopy measurements reveal a silicate-like Gd2O3/SiC interface. Furthermore, conduction and valence band discontinuities at the Gd2O3/6H-SiC interface were estimated with 1.9 eV and 1.2 eV, respectively. The fabricated capacitors exhibit suitable dielectric properties at room temperature; such as a dielectric constant of ε = 22, a leakage current of 10-8 A/cm2@1V and breakdown fields > 4.3 MV/cm for layers with 14 nm thickness. The CV measurements exhibit only small negative flat band shifts and a very small hysteresis, resulting from fixed charges or interface trap levels in the range of 1x1012 cm-2. These properties make Gd2O3 suitable for high-k application also for SiC.
N. Wright, C.M. Johnson, K. Vassilevski, I. Nikitina and A. Horsfall
A. Fissel et al., "Growth and Properties of Gadolinium Oxide Dielectric Layers on Silicon Carbide for High-K Application", Materials Science Forum, Vols. 556-557, pp. 655-658, 2007