Functionalizing the GaN()-(1×1) surface I. The chemisorption of aniline
2002; Elsevier BV; Volume: 499; Issue: 2-3 Linguagem: Inglês
10.1016/s0039-6028(01)01916-1
ISSN1879-2758
Autores Tópico(s)Electron and X-Ray Spectroscopy Techniques
ResumoChemisorption of aniline (C6H5NH2) on the GaN(0 0 0 1)-(1×1) Ga-polar surface has been studied using mainly X-ray-excited Auger electron, electron energy loss and ultraviolet photoemission spectroscopies (XAES, ELS and UPS, respectively). The XAES data show adsorption near room temperature with a total sticking probability of ∼0.05 and a saturation coverage of ∼0.28 phenyl rings per surface lattice site. The ELS data show removal of the characteristic surface-state band centered at ∼3.4 eV and the appearance of a π→π∗ loss at 6.5 eV due to CC bonds. In contrast, benzene (C6H6) does not chemisorb under these conditions. The UPS data, which have been analyzed with the aid of density functional theory molecular orbital calculations, indicate that adsorption occurs with a phenyl–NH group forming a Ga–N–Ga bridge. Adsorption causes a decrease in electron affinity (δχ≈−0.55 eV) due to a surface dipole layer, and measurement of δχ and of changes in band bending have been used to construct a partial energy level diagram for the aniline-covered surface.
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