arXiv subjects

Mingwen Zhao

Publications and source records attributed to Mingwen Zhao.

21 records · Page 2Linked to original sources

arXiv2012

Hybrid density functional study of band alignment in ZnO/GaN and ZnO/(Ga1-xZnx)(N1-xOx)/GaN heterostructures

The band alignment in ZnO/GaN and related heterostructures are crucial for the uses in solar harvesting technology. Here, we report our density functional calculations of the band alignment and optical properties of ZnO/GaN and ZnO/(Ga1-xZnx)(N1-xOx)/GaN heterostructures using a Heyd-Scuseria-Ernzerhof (HSE) hybrid functional. We found that the conventional GGA functionals underestimate not only the band gap but also the band offset of these heterostructures. Using the hybrid functional calculations, we show that the (Ga1-xZnx)(N1-xOx) solid solution has a direct band gap of about 2.608 eV, in good agreement with the experimental data. More importantly, this solid solution forms type-II band alignment with the host materials. A GaN/(Ga1-xZnx)(N1-xOx)/ZnO core-shell solar cell model is presented to improve the visible light adsorption ability and carrier collection efficiency.

cond-mat.mtrl-sci↗

arXiv2010

Natural charge spatial separation and quantum confinement of ZnO/GaN core/shell nanowires

We performed density-functional calculations to investigate the electronic structure of ZnO/GaN core/shell heterostructured nanowires (NWs) orientating along <0001> direction. The build-in electric filed arising from the charge redistribution at the {1-100} interfaces and the band offsets were revealed. ZnO-core/GaN-shell NWs rather than GaN-core/ZnO-shell ones were predicted to exhibit natural charge spatial separation behaviors, which are understandable in terms of an effective mass model. The effects of quantum confinement on the band gaps and band offsets were also discussed.

cond-mat.mtrl-sci↗

arXiv2009

Orientation-dependent stability and quantum-confinement effects of silicon carbide nanowires

The energetic stability and electronic properties of hydrogenated silicon carbide nanowires (SiCNWs) with zinc blende (3C) and wurtzite (2H) structures are investigated using first-principles calculations within density functional theory and generalized gradient approximation. The [111]-orientated 3C-SiCNWs are energetically more stable than other kinds of NWs with similar size. All the NWs have direct band gaps except the 3C-SiCNWs orientating along [112] direction. The band gaps of these NWs decrease with the increase of wire size, due to the quantum-confinement effects. The direct-band-gap features can be kept for the 3C-SiCNWs orientating along [111] direction with diameters up to 2.8 nm. The superior stability and electronic structures of the [111]-orientated 3C-SiCNWs are in good agreement with the experimental results.

cond-mat.mtrl-sci↗