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The deposition of elemental Se on epitaxial silicene on ZrB 2 thin films was investigated with synchrotron-based core-level photoelectron spectroscopy and low-energy electron diffraction. The deposition of Se at room temperature caused the appearance of Si 2 p peaks with chemical shifts of n × 0.51 ± 0.04 eV (n = 1-4), suggesting the formation of SiSe 2 . This shows that capping the silicene monolayer, without affecting its structural and electronic properties, is not possible with Se. The annealing treatments that followed caused the desorption of Se and Si, resulting in the etching of the Si atoms formerly part of the silicene layer, and the formation of bare ZrB 2 (0001) surface area. In addition, a ZrB 2 (0001)-(√7 × 3)R40.9° surface reconstruction was observed, attributed to a Se-termination of the surface of the transition metal diboride thin film. [ABSTRACT FROM AUTHOR]

GaN is directly grown on Si(111) by radio-frequency plasma-assisted molecular-beam epitaxy, and the surface is studied using in situ reflection high-energy electron diffraction (RHEED) and scanning tunneling microscopy (STM). By optimizing the growth condition, well-defined surface reconstructions are observed in atomically-resolved STM images after the additional Ga deposition, indicating the uniform N-polarity of the grown film. We show that N-rich condition in the initial GaN growth and slightly Ga-rich condition in the subsequent growth are critical in order to achieve monopolar uniform GaN films. [ABSTRACT FROM AUTHOR]