We report the results of our studies of ruthenium layer structures adsorbed on GaN(0001). Ruthenium was evaporated at room temperature under ultrahigh vacuum conditions onto n-type GaN substrates epitaxially grown on sapphire. When X-ray photoelectron spectroscopy confirmed the presence of Ru bonds in the deposited adlayer, the ultraviolet photoelectron spectroscopy shown a peak at the Fermi level as well as lines originating from ruthenium. The height of the Schottky barrier was calculated based on the data measured by X-ray photoelectron spectroscopy and ultraviolet photoelectron spectroscopy and amounts to 1.5 eV. The work function of Ru adlayer is 4.4 eV, while the electron affinity of n-GaN(0001) substrate equals 3.4 eV.

The electronic structures of Alq3/Si(111) and Alq3/LiBr/Si(111) interfaces are presented in this report. The studies were carried out in situ in ultrahigh vacuum by ultraviolet photoelectron spectroscopy. Alq3 and LiBr layers were vapour deposited onto a single crystal of n-type Si(111). The energy level diagrams were prepared for the structures. The formation of the LiBr interfacial layer results in a decrease of the energy barrier at the interface.

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This report presents results of research on electronic structure of three interfaces composed of organic layers of Alq3, Gaq3, or Erq3 deposited on GaN semiconductor. The formation of the interfaces and their characterization have been performed in situ under ultrahigh vacuum conditions. Thin layers have been vapor-deposited onto p-type GaN(0001) surfaces. Ultraviolet photoelectron spectroscopy (UPS) assisted by X-ray photoelectron spectroscopy (XPS) has been employed to construct the band energy diagrams of the substrate and interfaces. The highest occupied molecular orbitals (HOMOs) are found to be at 1.2, 1.7, and 2.2 eV for Alq3, Gaq3, and Erq3 layers, respectively. Alq3 layer does not change the position of the vacuum level of the substrate, in contrast to the other layers, which lower it by 0.8 eV (Gaq3) and 1.3 eV (Erq3). Interface dipoles at the phase boundaries are found to be −0.2, −0.9, −1.2 eV, respectively, for Alq3, Gaq3, Erq3 layers on GaN(0001) surfaces.

100) systems are presented in this report. Their energy level diagrams were prepared and discussed. The formation of the LiBr and KCl interfacial layers between an Alq 3 film and a Si(100) substrate results in a decrease of the energy barrier at the interface. The studies were carried out in situ in ultrahigh vacuum by ultraviolet photoelectron spectroscopy. Alq 3 as well as LiBr and KCl layers were vapour evaporated onto n-type Si(100) crystal. The electron affinity of clean Si(100) surface was 4.0 eV, and the position of the valence band maximum was 0.7 eV below E F . The energetic distance between the valence band maximum of Si(100) and the highest occupied molecular orbital level were 1.5, 2.6, and 2.2 eV, for the Alq 3 /Si(100), Alq 3 /LiBr/Si(100), and Alq 3 /KCl/ Si(100) systems, respectively.