Morphology and optical properties of MgO thin films on Mo(0 0 1)

• Published in: Chemical physics letters Vol. 430; no. 4; pp. 330 - 335
• Main Authors: Benedetti, S., Benia, H.M., Nilius, N., Valeri, S., Freund, H.J.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 30.10.2006
• ISSN: 0009-2614; 1873-4448
• DOI: 10.1016/j.cplett.2006.08.130

Thin MgO films have been grown on Mo(0 0 1) and studied by means of STM, LEED and local photon emission spectroscopy, performed by injecting electrons from the STM tip into the sample surface. The paper provides an overview over the MgO morphology and optical characteristics as a function of film thickness. Thin MgO films with a nominal thickness ranging between 1 and 60 ML have been grown on a Mo(0 0 1) surface. The film morphology was studied by LEED and STM, revealing the presence of a coincidence pattern with the Mo support in the low coverage regime, a dislocation network at medium thickness and a rather flat and defect-poor MgO surface for thicker layers. The MgO optical properties were investigated as a function of film thickness by analyzing electro-luminescence spectra obtained via electron injection from the STM tip into well-defined surface areas. The spectra are characterized by two distinct emission bands at 3.1 and 4.4 eV. Their origin is discussed in the light of earlier photo-luminescence measurements on MgO nanocubes and smokes.