Modification of Electronic Structure of n-GaN(0001) Surface by N⁺-Ion Bombardment

Abstract

The electronic structure of n-type GaN(0001) surface and its modification by N + ion bombardment are presented in this report. The studies were carried out in situ in ultrahigh vacuum by ultraviolet photoelectron spectroscopy, X-ray photoelectron spectroscopy, and low-energy electron diffraction. Low-energy N + ion bombardment, which was done using an ion gun at an energy of 200 eV, leads to nitriding of the surface. The process changes the surface stoichiometry and, consequently, provides formation of a disordered altered GaN layer. The calculated electron affinity of the clean n-GaN surface of 3.4 eV and band bending of 0.2 eV became changed after bombardment to 2.9 eV and 0.8 eV, respectively. The obtained difference in valence band maximum between the clean sample and the bombarded one was 0.6 eV.

The Influence of Oxygen and Carbon Contaminants on the Valence Band of p-GaN(0001)

“…This may also stem from the fact that on the ion bombarded surface the photovoltage effect can be weaker or even does not occur at all. This is also consistent with other works [14,23], where N + -ion bombardment was applied.…”

Properties of Bare and Thin-Film-Covered GaN(0001) Surfaces

“…Ion bombardments may introduce defects and preferentially remove nitrogen atoms [62,70,71]. To eliminate this effect, the postbombardment annealing method or low-energy N-ion bombardment can be utilized [72][73][74]. The most convenient and simplest technique of surface preparation in UHV is annealing.…”

“…Therefore, in order to counteract the changes in GaN surface properties and its degradation, less-invasive cleaning processes are needed. In [73,74], a process of bombardment with nitrogen ions, with a relatively low energy level of 200 eV, was proposed. This solution enables the cleaning of the surface by sputtering, yet is much less destructive and also compensates for nitrogen loss from the near-surface region.…”

Investigation of memory effect in Au/(Ti-Cu)Ox-gradient thin film/TiAlV structure

“…Taking into consideration the band gap energy of the thin films equal to 2.80 eV, the thin film surface exhibits p-type conduction. The electron affinity () of the thin film surface was equal to 2.41 eV and was calculated based on the relationship [55,56] :…”