Interfacial Polarization of Thin Alq3, Gaq3, and Erq3 Films on GaN(0001)

This report presents results of research on electronic structure of three interfaces composed of organic layers of Alq(3), Gaq(3), or Erq(3) 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 Alq(3), Gaq(3), and Erq(3) layers, respectively. Alq(3) 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 (Gaq(3)) and 1.3 eV (Erq(3)). Interface dipoles at the phase boundaries are found to be -0.2, -0.9, -1.2 eV, respectively, for Alq(3), Gaq(3), Erq(3) layers on GaN(0001) surfaces.

Automated summary

This report presents the research results on the electronic structure of three interfaces consisting of organic layers of Alq(3), Gaq(3), or Erq(3) deposited on GaN semiconductor. The formation and characterization of the interfaces were performed in situ under ultrahigh vacuum conditions. The band energy diagrams of the substrate and interfaces were constructed using ultraviolet photoelectron spectroscopy (UPS) assisted by X-ray photoelectron spectroscopy (XPS). The study found that the highest occupied molecular orbitals (HOMOs) of Alq(3), Gaq(3), and Erq(3) layers are at 1.2, 1.7, and 2.2 eV, respectively. The Alq(3) layer does not affect the position of the vacuum level of the substrate, unlike the Gaq(3) and Erq(3) layers, which lower it by 0.8 eV and 1.3 eV, respectively. The interface dipoles at the phase boundaries were found to be -0.2, -0.9, and -1.2 eV for Alq(3), Gaq(3), and Erq(3) layers on GaN(0001) surfaces.