Construction of van der Waals substrates for largely mismatched heteroepitaxy systems using first principles

Shi, Zhiming; Sun, Xiaojuan; Jia, Yuping; Liu, Xinke; Zhang, ShanLi; Qi, Zhanbin; Li, DaBing

doi:10.1007/s11433-019-1448-3

Cited by 11 publications

(6 citation statements)

References 61 publications

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“…Here we employ a four-layer GaN slab and two substrates, graphene (Gra) and silicon carbide (SiC), as examples to investigate the substrate effect. First, we cover the wurtzite or 4 | 8 slabs on graphene, acting as vdW epitaxy 41,42 . After structural relaxation, the 4 | 8 structure remains in the initial configuration, as shown in Fig.…”

Section: Substrates Effectmentioning

confidence: 99%

Elimination of the internal electrostatic field in two-dimensional GaN-based semiconductors

et al. 2020

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GaN-based semiconductors are promising materials for solid-state optoelectronic applications. However, the strong internal electrostatic field (IEF) along the [0001] direction is a serious problem that harms the efficiency of lighting devices based on GaNbased semiconductors due to the quantum confined Stark effect. Here we theoretically predict a method, reducing the dimensions from bulk to two-dimensional (2D) structures, to fundamentally remove the IEF. After thinning the materials to several nanometers, the wurtzite configuration (with strong IEF) spontaneously transform to the haeckelite (4 | 8) configuration (without IEF) due to the more stable neutral surface in the 4 | 8 configuration. Meanwhile, the 4 | 8 configuration maintain optoelectronic properties comparable to or even better than those of the wurtzite configuration. By carefully analyzing the interaction between 2D GaN and different types of substrates (SiC and graphene), we not only provide clear physical insights for experimental results but also address a "thickness-controlled" vdW epitaxy scheme to experimentally realize the 4 | 8 configuration. We believe that the 4 | 8 configuration without IEF is a prospective material for diverse optoelectronic applications. In addition, we propose a point of view in engineering the properties of GaN-based semiconductors.

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Section: Substrates Effectmentioning

confidence: 99%

Elimination of the internal electrostatic field in two-dimensional GaN-based semiconductors

et al. 2020

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“…on h-BN). 27,28 More importantly, the GaN islands at the wrinkles and flat areas have the same in-plane orientation, which lays the foundation for the subsequent acquisition of single-crystal GaN films. In order to further analyze the nucleation characteristics of the GaN buffer layer on h-BN, the crosssectional TEM characterizations of GaN island I at the wrinkles and GaN island II in the flat areas were carried out.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

Growth Mechanism of Exfoliable GaN by van der Waals Epitaxy on Wrinkled Hexagonal Boron Nitride

et al. 2023

Crystal Growth & Design

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The excellent physical and chemical properties of two-dimensional (2D) materials provide the possibility to promote the further development of 3D III-nitride semiconductors. Growing GaN films on 2D materials like hexagonal boron nitride (h-BN) can reduce the defects and stress caused by lattice mismatch and thermal mismatch and improve the crystal quality of GaN. Here, the growth mechanism of exfoliable GaN films grown on processed wrinkled h-BN/sapphire substrates by van der Waals epitaxy is reported. The processed wrinkled h-BN is obtained from natural wrinkled h-BN through O 2 plasma treatment. The O 2 plasma creates new atomic steps in the wrinkles and also additional defects in the flat areas. Metal-organic chemical vapor deposition was used to grow GaN, and it was found that GaN preferentially nucleated along the processed wrinkles. The physical mechanism of preferential nucleation of GaN along h-BN wrinkles was investigated with first-principles calculations, which reveals that compared with flat areas, the wrinkles showed greater N atom adsorption energy (−5.55 eV). The complete growth process of GaN nucleation along the wrinkles, followed by lateral growth of islands and finally merging to form a flat single-crystal GaN film, was fully demonstrated. The obtained GaN film has a typical atomic-step terrace, a dislocation density of 7.23 × 10 8 cm −2 , and a low compressive stress of 0.095 GPa. Due to the weak van der Waals force between the h-BN layers, the obtained GaN film can be easily released. Our work provides a new strategy for the growth of high-quality exfoliable GaN films on 2D materials, laying the foundation for the preparation of transferable GaN flexible devices.

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“…Due to the valence electrons accumulation around the surface of S atoms in the MoS bonds of MoS 2 insert layer, the Coulomb interactions of the S atoms and Al atoms are stronger than that with the N atoms. [51] In this way, the Al atoms prefer to absorb on the MoS 2 insert layer (Process I) while the N atoms tend to desorb from its surface (Process II), showing the higher reaction activity between the Al and S atoms. During the chemical reaction in the MOCVD system, the species of Al-N pairs are formed.…”

Section: The Polarity Control Mechanism For the Gan Epilayersmentioning

confidence: 99%

The van der Waals Epitaxy of High‐Quality N‐Polar Gallium Nitride for High‐Response Ultraviolet Photodetectors with Polarization Electric Field Modulation

Chen

Shi

Zhang

et al. 2021

Adv Elect Materials

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is restricted by the intrinsically large lattice and thermal mismatch between the epilayer and foreign substrate, which induces a mass of dislocations and the strong residual stress. [8] Generally, the large stress in III-nitrides triggers the risk for epilayer crack and the high-density dislocations act as carrier recombination centers and leakage channels, which would both lower the device performance and degrade its uniformity for the mass production. Traditional buffer layers including low-temperature aluminium nitride (AlN) nucleation layer, [9] periodic superlattice structure, [10,11] and Al metal film [12] have been widely applied, however, the total residual stress in epitaxial systems remain unchanged. In other words, the mismatch-induced dislocation and stress are partially confined in the buffer layer, and thus the optimization of crystalline quality and residual stress for III-nitride epilayers is limited. Recently, the high-quality and stress-free III-nitrides epitaxy on 2D layers (including h-BN and graphene) are developed, which is socalled as van der Waals epitaxy. [13][14][15] This innovation relies on the excellent stability and weak van der Waals interlayer interaction of 2D insert layers, which fundamentally solves the trouble induced by the heteroepitaxy. As the trade-off, the atomic flatness surface and scarce dangling bonds of h-BN and graphene have made difficulties in III-nitride nucleation. Unless the insert 2D layers are broken or atom-doped by specific treatments, including plasma or in situ nitridation, the epitaxial III-nitride could be in a high crystalline quality with the coalescent surface. [16,17] Apart from the crystalline optimization of III-nitrides, it is known that the typical III-nitride with wurtzite crystalline structure has an inversion symmetry along the c-axis orientation, possessing two opposite polar faces of Ga-polar ([0001] direction) and N-polar ([0001] direction). [18] The spontaneous polarization vector of III-nitride is determined by the polarity orientation, and thus different types of charges would be generated. As a consequence, the optical as well as electrical properties of III-nitride can be adjusted by controlling the polarization orientation. Several works prove that the proper assembly of metal-polar and N-polar III-nitrides could invert High-quality and polarity-controlled III-nitride is crucial for realizing highperformance and new types of device designs with rich functionalities, but there are still many difficulties for obtaining N-polar III-nitrides till now. In this work, the van der Waals epitaxy of high-quality N-polar gallium nitride (GaN) is reported by innovatively inserting a thin MoS 2 layer. Due to the remission of thermal and lattice mismatch by the week van der Waals force in 2D MoS 2 insert layer, the N-polar GaN exhibits high crystalline quality and reduced residual stress. The proposed atom deposition kinetics for the van der Waals epitaxy of the polarity-controlled aluminium nitride nucleation layer and GaN epilayer on the MoS 2 l...

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Construction of van der Waals substrates for largely mismatched heteroepitaxy systems using first principles

Cited by 11 publications

References 61 publications

Elimination of the internal electrostatic field in two-dimensional GaN-based semiconductors

Elimination of the internal electrostatic field in two-dimensional GaN-based semiconductors

Growth Mechanism of Exfoliable GaN by van der Waals Epitaxy on Wrinkled Hexagonal Boron Nitride

The van der Waals Epitaxy of High‐Quality N‐Polar Gallium Nitride for High‐Response Ultraviolet Photodetectors with Polarization Electric Field Modulation

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