Control of Epitaxial Growth Plane of Rh Thin Films on A-Plane Sapphire by Sputter Deposition

Abstract

We have expected that the epitaxial growth of (111)Rh and (001)Rh films with a thickness of 100 nm can be controlled on (11 2 0) sapphire by changing sputtering parameters using an ultrahigh-vacuum sputtering system, because the lattice mismatches between the two-dimensional superlattice cells of (111)Rh/(11 2 0) sapphire and (001)Rh/(11 2 0) sapphire systems are the same. Thus, the effect of rf sputtering power (Prf) on each epitaxial growth was examined, and the crystal quality, surface morphology, resistivity and temperature coefficient of resistivity (TCR) of the prepared Rh films were evaluated. As a result, it is revealed that both the (111)Rh and (001)Rh films can be grown epitaxially on (11 2 0) sapphire by adjusting only the values of Prf (deposition rate: Rd) under the condition of the substrate temperature (Ts) of 500 °C. In addition, it is confirmed that the average surface roughness of these epitaxially grown Rh films is below approximately 1.2 nm, and resistivity of approximately 5.6 ×10-6 Ω cm is obtained.