Ab Initio Analysis of the Interactions of GaN Clusters with Oxygen and Water

Abstract

We calculate the interactions of oxygen and water with the Ga-face of GaN clusters, which could be used as testbeds for the actual Ga-face on GaN crystals of importance in electronics; however, our additional goal is the analysis of the nanoclusters for several other applications in nanotechnology. Our results show that the local spin plays an important role in these interactions. It is found that the most stable interaction of O2 and the GaN clusters results in the complete dissociation of the O2 molecule to form two Ga–O–Ga bonds, while the most stable interaction between a H2O molecule and the GaN clusters is the complete dissociation of one of the O–H bonds to form a Ga–O–H bond and a Ga–H bond.

Atomistic-Level Description of GaN/Water Interface by a Combined Spectroscopic and First-Principles Computational Approach

“…We have chosen the GaN(0001) surface/water interface as a model system because GaN has better crystal quality compared to other photocatalysts, which makes easier the comparison between computational and experimental results. It is worth mentioning that GaN electrode has attracted considerable attention for photocatalytic applications. − Water adsorption on GaN surface itself is also of interest in the context of surface chemistry; it has been studied extensively by first-principles calculations, − and several attempts have been made to determine the surface structure using photoelectron spectroscopy. − Recently, Zhang and Ptasinska pointed out the strong correlation between the electronic and chemical properties of the water adsorbed GaN(0001) surface . However, in spite of substantial effort, an atomistic model for the physisorbed and chemisorbed water layers has not yet been defined …”

Effect of Water Vapor and Surface Morphology on the Low Temperature Response of Metal Oxide Semiconductor Gas Sensors

“…A second group of materials that exhibits a similar kind of low-temperature response, is III-nitride materials both in the form of AlGaN/GaN high electron mobility transistors (HEMT) with flat surface morphologies [ 14 , 15 , 16 , 17 , 18 , 19 ] as well as in the form of GaN/InGaN nanowire heterostructures [ 20 , 21 , 22 ]. These effects can be attributed to the fact that III-nitride surfaces tend to develop surface oxides when exposed to ambient air which makes them similar to conventional MOx materials [ 23 , 24 , 25 , 26 , 27 , 28 ]. A third group of materials that exhibits a well-documented low low-temperature gas response is hydrogenated diamond.…”

Removal of Water Adsorbates on GaN Surfaces via Hopping Processes and with the Aid of a Pt4 Cluster: An Ab Initio Study

“…To obtain a microscopic picture of the intrinsic mechanism and hence predict suitable photocatalysts, many theoretical calculations estimated the band gaps and band edge positions of known and potential materials. ,− Some of these works even analyzed band structures and/or predicted the light absorption spectra. − Many other theoretical works studied the water/photocatalyst interface structure and/or thermal dynamics of water molecules and adsorbates to understand the water splitting processes from an atomic point of view. ,− In one of our previous works, we observed that it is much easier to produce oxygen gas molecules than H 2 on (101̅0) nonpolar surface, while the polar surface behaves in a reverse way. The paths for removing other water adsorbates (hydroxyl groups, hydrogen, and oxygen adatoms) from GaN surfaces are still undetermined.…”