Cs/NF3 adsorption on [001]-oriented GaN nanowire surface: A first principle calculation. (November 2017)

• Record Type: Journal Article
• Authors: Diao, Yu; Liu, Lei; Xia, Sihao; Kong, Yike
• Is Part Of: Superlattices and microstructures. Volume 111(2017)
• Page Start: 73
• Page End: 80
• Publication Date: 2017-11
• Subjects: Cs/NF3 adsorption -- GaN nanowire -- First principles; Superlattices as materials -- Periodicals; Microstructure -- Periodicals; Semiconductors -- Periodicals; Superréseaux -- Périodiques; Microstructure (Physique) -- Périodiques; Semiconducteurs -- Périodiques; 621.38152
• DOI: 10.1016/j.spmi.2017.06.022
• Languages: English
• ISSNs: 0749-6036

Abstract

Abstract: In this study, the adsorption mechanism of Cs/NF3 on the [001]-oriented GaN nanowire surface is investigated by using the density function theory based on first-principles. In the Cs/NF3 co-activation process, the system is inclined to form NF3 -in structure. Through the calculation results of adsorption energy, NF3 molecule adsorption tends to take an orientation with F atoms on top and the most favorable adsorption site is BGa-N . The NF3 activation process can further cut down the work function of the Cs-covered nanowire surface only when Cs coverage is 0.75 ML and 1 ML, which can be explained by the double dipole moment theory. With increasing Cs coverage, the valence band and conduction band both shift to lower energy side, contributing to the appearance of a downward band bending region and promoting the escape of surface photoelectrons. After NF3 molecule adsorption, the peak of total density of states near Fermi level increase due to the orbital hybridization between NF3 -2s, Cs-5s states and N-2p states, which strengthen the conductivity of the nanowire surface and leads to the metallic properties. All these calculations may direct the Cs/NF3 activation process of GaN nanowire optoelectronic devices. Highlights: Cs/NF3 adsorption mechanism on GaN nanowire surface are investigated. The surface morphology is calculated through first principles for the first time. The properties of GaN nanowire surface can be improved by Cs/NF3 activation. All these calculations may direct the activation process of GaN nanowire devices.