ORCID Profile
0000-0002-1406-1256
Current Organisations
Wuhan University
,
Hong Kong University of Science and Technology
Does something not look right? The information on this page has been harvested from data sources that may not be up to date. We continue to work with information providers to improve coverage and quality. To report an issue, use the Feedback Form.
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 07-2017
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 10-2017
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 07-2016
Publisher: IOP Publishing
Date: 13-06-2018
Publisher: AIP Publishing
Date: 08-2020
DOI: 10.1063/5.0012685
Abstract: The below bandgap optical transitions of an aluminum nitride (AlN) crystal grown on a tungsten (W) substrate by physical vapor transport (PVT) are investigated by below-bandgap-excited photoluminescence (PL) spectroscopy and first-principles calculations. Oxygen (O) is the only impurity in the AlN-on-W crystal grown by PVT. By analyzing the excitation-power-, excitation-photon-energy-, and temperature-dependence of the PL spectra, the emission peaks of defect complexes involving aluminum vacancy (VAl) and substitutional oxygen (ON) with different spatial and atomic configurations, i.e., VAl–ON and VAl–2ON with ON featuring axial or basal configurations, are identified. It is revealed that two different charging states coexist in thermal equilibrium for each configuration of VAl–ON complexes. The optical transitions between the conduction band and (VAl–ON)2− and/or (VAl–2ON)1− contribute the UV emissions and those between the valence band and (VAl–ON)1− or (VAl–2ON)0 contribute the red emissions.
Publisher: Elsevier BV
Date: 04-2014
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 12-2015
Publisher: IEEE
Date: 05-2017
Publisher: IEEE
Date: 12-2015
Publisher: IEEE
Date: 06-2016
Publisher: IEEE
Date: 12-2016
Publisher: IOP Publishing
Date: 08-05-2019
Publisher: Springer Science and Business Media LLC
Date: 19-10-2015
DOI: 10.1038/SREP15191
Abstract: Cu/Cu 2 O composite structures have been discovered to show sizable ferromagnetism (FM) with the potential applications in spintronic devices. To date, there is no consensus on the FM origin in Cu/Cu 2 O systems. Here, first principles calculations are performed on the interface structure to explore the microscopic mechanism of the FM. It is found that only the Cu vacancy (V Cu ) adjacent to the outermost Cu 2 O layer induces a considerable magnetic moment, mostly contributed by 2 p orbitals of the nearest-neighbor oxygen atom (O NN ) with two dangling bonds and 3 d orbitals of the Cu atoms bonding with the O NN . Meanwhile, the charge transfer from Cu to Cu 2 O creates higher density of states at the Fermi level and subsequently leads to the spontaneous FM. Furthermore, the FM could be modulated by the amount of interfacial V Cu , governed by the interfacial Cu diffusion with a moderate energy barrier (~1.2 eV). These findings provide insights into the FM mechanism and tuning the FM via interfacial cation diffusion in the Cu/Cu 2 O contact.
Publisher: AIP Publishing
Date: 04-2020
DOI: 10.1063/5.0005648
Abstract: Solar to fuel energy conversion is one of the momentous topics nowadays considering the urgent demand for clean energy supplies. In this work, the tunable electronic and optical properties of III-nitride/ZnO 2D/2D heterostructures (including GaN/ZnO, AlN/ZnO, and GaN/AlN) by strain engineering were investigated by first-principles calculations. The studied heterostructures feature a small interlayer distance, with the cation of one layer directly above the anion of the other layer, and vice versa. This leads to a strong binding energy and interlayer coupling across the heterostructure. The built-in field induced by the charge redistribution facilitates the photoexcited carrier migration, which is beneficial to the photocatalytic water splitting application. The stable III-nitride/ZnO heterostructures exhibit decent band edge positions with biaxial strain engineering and feature an enhancement of optical absorption under tensile strain. Our results indicate that the III-nitride/ZnO 2D/2D heterostructures are promising photocatalysts for solar to hydrogen generation by water splitting.
No related grants have been discovered for Zhaofu Zhang.