Robust Type‐II Band Alignment and Stacking‐Controlling Second Harmonic Generation in GaN/ZnO vdW Heterostructure

Abstract

Most traditional 2D materials have small bandgaps, resulting in low laser damage thresholds and limiting their applications in the ultraviolet region. Recently experimentally synthesized 2D GaN and ZnO can be such candidates due to their wide bandgaps, high charge mobilities, and optical transparency. Here, the van der Waals heterostructure GaN/ZnO is predicted that can exhibit both wide bandgap and strong second harmonic generation (SHG) response by compelling simulations. The results show the heterostructure always exhibits type‐II band alignment under all probable stacking configurations. The out‐of‐plane SHG coefficients are up to 90 pm V−1 at 400 nm, comparable to those of MoS2 and MoSe2 and higher than most 3D crystals. Interestingly, the positions are enhanced with localized, symmetric, and stacking‐dependent features in the Brillouin zone. This peculiar momentum space behavior is originated from the relative strength of two distinct mechanisms contributing to the second‐order nonlinear optical (NLO) response, that is, a purely interband transition part and a mixed interband‐intraband contribution. Thus, this study proposes that GaN/ZnO heterostructure may be an efficient and high laser damage thresholds (LDTs) NLO material and an interesting platform for studying NLO optical properties.

Ternary Penta-CoXS (X = Se and Te): 2D Monolayers with Coexistence of Antiferromagnetic, Auxetic, Photocatalytic, and Piezoelectric Features

“…In addition to a suitable band gap and proper band alignment, the optical absorption capability of 2D materials plays an essential role in photocatalytic applications . To study the optical response of the penta-CoXS (X = Se and Te) nanosheet, the optical absorption spectra along the in-plane direction are investigated, as shown in Figure c,d.…”

“…In addition to a suitable band gap and proper band alignment, the optical absorption capability of 2D materials plays an essential role in photocatalytic applications. 78 To study the optical response of the penta-CoXS (X = Se and Te) nanosheet, the optical absorption spectra along the in-plane direction are investigated, as shown in Figure 6c,d. A large portion of absorption falls into the visible range, and the optical absorption coefficients are on the order of 10 5 cm −1 magnitude, indicating that the penta-CoXS (X = Se and Te) monolayers possess efficient light-harvesting capabilities, making them favorable candidates for photocatalyzing water splitting.…”

Theoretical insights into the lattice thermal conductivity and thermal expansion of CoNiFe medium-entropy alloys

“…Recently, the thermodynamic properties of high-entropy alloys have also attracted extensive research attention, particularly their thermal conductivity. 16–25 For example, Farias et al 17 calculated the lattice thermal conductivity of random solid solution Cantor alloys using the Green–Kubo method in the temperature range from 0 K to 300 K. The thermal conductivity at 300 K was found to be within 21% of the experimental results. 18 Chou et al 19 studied the thermal conductivity of Al x CoCrFeNi (0 ≤ x ≤ 2), which is significantly lower than that of the pure metal.…”

Computational understanding of the coalescence of metallic nanoparticles: a mini review

“…Both MD simulation and density functional theory (DFT) calculations are computational approaches capable of simulating the movements of atoms or molecules. As compared with DFT calculations, [29][30][31][32] MD simulation is suitable for longer times and larger-size scales. 18,19,21 In MD simulation of metallic nanoparticles, the metal atoms in the nanoparticles interact with each other and move to energetically favorable sites, which is able to reproduce the dynamic evolution of the metallic system according to experimental conditions.…”