Study of the early stages of Cu/6H–SiC(0 0 0 -1) interface formation

Abstract

The early stages of the Cu/SiC interface formation at room temperature and the influence of annealing were investigated on the carbon-face of the single crystal n-type 6H–SiC, by X-ray photoelectron and auger electron spectroscopy (XPS/XAES), low energy electron diffraction and work function (WF) measurements. Upon stepwise copper evaporation in UHV up to a thickness of 5–10 monolayers (ML) at RT, the binding energy of the XPS Cu2p 3/2 core level peak shifted from 933.6±0.1 eV, below 0.1 ML coverage, to 932.7 eV for the final metallic Cu deposit. The WF, following an initial steep decrease from the clean SiC substrate value of 4.4 down to 4.0 eV up to 0.1 ML, increased then gradually to the metallic Cu value of ∼4.75 eV after approximately 5 ML of Cu. The growth of the film was initially via 2D-cluster formation, and exhibited a 3D character beyond 1–2 ML of Cu. The height of the Schottky barrier for the Cu/6H–SiC(0 0 0 -1) contact was found by XPS to be 1.5±0.1 eV. Annealing of the contact up to 520 K caused small changes in the Cu and SiC XPS peak intensities accompanied by a 0.3 eV increase of the WF, indicating small structural changes within the film and gave rise to a slight change of the Schottky barrier height to 1.6±0.1 eV. The results do not indicate any significant silicide formation at 520 K.