Growth mechanisms and band bending in Cu and Pt on Ge(001) investigated by LEED and photoelectron spectroscopy

We investigate band bending effects occurring at the interface between atomically clean Ge(001) and molecular beam epitaxy (MBE) deposited copper and platinum. Low energy electron diffraction (LEED) confirmed the crystallinity of the surface, evidenced the formation of (2×1) and (1×2) reconstruction...

Full description

Saved in:
Bibliographic Details
Published in:Surface science 2016-11, Vol.653, p.97-106
Main Authors: Tănase, Liviu Cristian, Bocîrnea, Amelia Elena, Şerban, Andreea Bianca, Abramiuc, Laura Elena, Bucur, Ioana Cristina, Lungu, George-Adrian, Costescu, Ruxandra Maria, Teodorescu, Cristian Mihail
Format: Article
Language:English
Subjects:
Band bending
Growth mechanisms
Metal-semiconductor contact
Metal-semiconductor interface
Schottky contact
X-ray photoelectron spectroscopy
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:We investigate band bending effects occurring at the interface between atomically clean Ge(001) and molecular beam epitaxy (MBE) deposited copper and platinum. Low energy electron diffraction (LEED) confirmed the crystallinity of the surface, evidenced the formation of (2×1) and (1×2) reconstructions, and revealed that it is strongly affected with metal deposition. X-ray photoelectron spectroscopy (XPS) data let us assume a Stranski–Krastanov growth mechanism and confirmed that the observed band bending is associated to an ohmic contact in both cases. For the platinum contact, the high values of the apparent inelastic mean free path (IMFP) derived from the evolution of the XPS intensities indicate a prevalence of mixture of Pt with Ge nearby the interface. Pt deposited on Ge(001) does not behave like a Schottky contact, as one may have expected due to the higher work function of platinum. The observed effect is similar to the case where interfacial Pt had a lower work function by 2.25/1.96eV than that of metallic Pt. We propose a model to explain this fact by the effective mass variation or to the conduction band broadening due to the strong intermixing of platinum with germanium under the surface. [Display omitted] •Synthesis of Cu/Ge and Pt/Ge junctions on clean Ge(001) surface by molecular beam epitaxy•Mixed growth mechanisms (islands+continuous layer) in the both cases•Ohmic contacts for both Cu/Ge and Pt/Ge•Schottky barrier height of −0.68/−0.80eV for Cu/Ge and of −1.31eV for Pt/Ge derived by X-ray photoelectron spectroscopy•Work function lowering when Pt intermixes Ge
ISSN:0039-6028
1879-2758
DOI:10.1016/j.susc.2016.06.006