Comparative study of erbium disilicide thin films grown in situ under ultrahigh vacuum or ex situ with a capping layer

Erbium disilicide (ErSi2-x) thin films grown by two different techniques are compared using a variety of characterization techniques, both electrical and physical. The first technique involves Er deposition and annealing under ultrahigh vacuum and the second one focuses on Ti/Er/Si(100) stacks evaporated under high vacuum and heated ex situ by rapid thermal annealing. Crystalline phase identification by X-ray diffraction reveals the formation of ErSi2-x for all the studied samples. Cross-sectional transmission electron microscopy shows that the Ti cap transforms into Ti-Si compounds. The efficient stripping of the capping layer is also demonstrated. Atomic force microscopy evidences the formation of inverted pyramidal defects in both cases, with some improvement for the Ti-capped samples. X-ray photoelectron spectroscopy depth profiles show that the ErSi2-x films and the ErSi2-x/Si interfaces are oxygen-free. The extracted Schottky barrier height of ErSi2-x/n-Si contacts lies around 0.3 eV notwithstanding the annealing temperature or the growth technique. It thus demonstrates a route to form ErSi2-x thin films that advantageously compares with reference ultrahigh vacuum samples with less stringent fabrication conditions