The interfacial properties of erbium films on the two polar faces of 6H-SiC (0001)

The interfaces formed by Er evaporation on the two polar faces of n-type 6H-SiC(0001) were investigated by X-ray photoelectron spectroscopy (XPS), low enery electron diffraction (LEED) and work function (WF) measurements. Erbium was deposited at room temperature from submonolayers up to 20 Angstrom thick and then gradually annealed up to 1000 K. Increasing Er deposition led to a weakening and eventual disappearance of the 1 x 1 LEED pattern of the clean surface, a decrease of the WF to the value of metallic Er (similar to 3 eV), after a 5 Angstrom Er deposition and the formation of a Schottky barrier with a height of (1.2 +/- 0.2) eV for both polar faces of the substrate. In both cases, annealing of the Er films up to 1000 K led to no significant change of the WF, whereas the height of the Schottky barrier increased to a value of (1.6 +/- 0.1) eV. The results were compared with Er deposition data on hexagonal SiC(0001) with different surface preparation. (C) 2001 Elsevier Science B.V. All rights reserved.