Growth optimization and electronic structure of ultrathin CoO films on Ag(001): A LEED and photoemission study

• Published in: Journal of crystal growth Vol. 487; pp. 28 - 33
• Main Authors: Barman, Sukanta, Menon, Krishnakumar S.R.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01.04.2018; Elsevier BV
• Subjects: A1. Interfacial states; A1. Surface structure; A3. Molecular beam epitaxy; B1. Oxides; Electronic structure; Interfacial bonding; Metal oxides; Molecular beam epitaxy; Optimization; Oxygen; Parameters; Partial pressure; Photoelectric emission; Pressure; Substrates; Valence band; B1. Oxides; A1. Interfacial states; A3. Molecular beam epitaxy; A1. Surface structure
• ISSN: 0022-0248; 1873-5002
• DOI: 10.1016/j.jcrysgro.2018.02.017

•Growth optimization of CoO(001) ultrathin films on Ag(001).•Observation of mosaic LEED pattern due to misfit dislocations up to 10 ML film coverage.•Effects of growth conditions and post-growth treatments on valence electronic structure.•Evidence of interfacial valence band states in the low coverage regime. We present here a detailed growth optimization of CoO thin film on Ag(001) involving the effects of different growth parameters on the electronic structure. A well-ordered stoichiometric growth of 5 ML CoO film has been observed at 473 K substrate temperature and 1 × 10−6 mbar oxygen partial pressure. The growth at lower substrate temperature and oxygen partial pressure show non-stoichiometric impurity phases which have been investigated further to correlate the growth parameters with surface electronic structure. The coverage dependent valence band electronic structure of the films grown at optimized condition reveals the presence of interfacial states near the Fermi edge (EF) for lower film coverages. Presence of interfacial states in the stoichiometric films rules out their defect-induced origin. We argue that this is an intrinsic feature of transition metal monoxides like NiO, CoO, MnO in the low coverage regime.