Tuning the electronic properties and band offset of h-BN/diamond mixed-dimensional heterostructure by biaxial strain
At a Glance
Section titled âAt a Glanceâ| Metadata | Details |
|---|---|
| Publication Date | 2024-04-24 |
| Journal | Scientific Reports |
| Authors | Yipu Qu, Hang Xu, Jiping Hu, Fang Wang, Yuhuai Liu |
| Institutions | Zhengzhou University |
| Citations | 8 |
| Analysis | Full AI Review Included |
Executive Summary
Section titled âExecutive SummaryâThis research utilizes first-principles calculations (DFT) to analyze and tune the electronic properties and band offsets of monolayer hexagonal boron nitride (h-BN) integrated with various terminated diamond (111) substrates.
- Core Value Proposition: Biaxial strain is confirmed as an effective method to precisely regulate the bandgap width and type (direct/indirect) of h-BN/diamond heterostructures, expanding their utility in advanced electronics.
- Interface Stability: Four systemsâh-BN/H, O, F, and OH-terminated diamondâwere constructed and confirmed to be thermally stable Type-II semiconductors, promoting efficient electron-hole separation.
- Optimal Charge Separation: The h-BN/H-diamond system exhibits the largest Valence Band Offset (VBO) of 2.61 eV, indicating superior hole confinement and suitability for leakage current reduction.
- Strain-Induced Transitions: Applying biaxial strain (ranging from -12% to 12%) induces direct-to-indirect bandgap transitions in all systems. Notably, h-BN/O-diamond transitions from a semiconductor to a metal under high compressive strain (less than -10%).
- Bandgap Control: The bandgap of h-BN/H-diamond decreases linearly with strain, while the bandgaps of O, F, and OH-terminated systems generally increase linearly across the full strain range.
- Mechanism: Surface termination significantly affects interface binding energy and charge transfer, with H-termination playing a key role in forming a highly conductive two-dimensional hole gas (2DHG).
Technical Specifications
Section titled âTechnical Specificationsâ| Parameter | Value | Unit | Context |
|---|---|---|---|
| Bulk Diamond Bandgap (HSE) | 5.47 | eV | Unstrained, Indirect semiconductor |
| Monolayer h-BN Bandgap (HSE) | 5.9 | eV | Unstrained, Indirect semiconductor |
| Optimized h-BN Lattice Constant (a0) | 2.504 | A | Monolayer h-BN |
| Lattice Mismatch (h-BN/Diamond) | less than 0.2 | % | (2x2) h-BN / (1x1) Diamond model |
| h-BN/H-diamond Bandgap (PBE) | 2.07 | eV | Unstrained, Indirect |
| h-BN/H-diamond VBO | 2.61 | eV | Type-II offset, Largest VBO |
| h-BN/O-diamond Bandgap (PBE) | 1.01 | eV | Unstrained, Direct |
| h-BN/O-diamond EBE (Binding) | -0.236 | eV/A2 | Strongest interface coupling |
| h-BN/F-diamond Bandgap (PBE) | 1.52 | eV | Unstrained, Indirect |
| h-BN/OH-diamond Bandgap (PBE) | 2.25 | eV | Unstrained, Direct |
| Strain Range Applied | -12 to 12 | % | Biaxial strain (compressive to tensile) |
| Vacuum Layer Thickness | 15 | Angstrom | Separating periodic images |
| MD Simulation Temperature | 300 | K | Thermal stability verification (NVE method) |
Key Methodologies
Section titled âKey MethodologiesâThe study relied on Density Functional Theory (DFT) calculations using the PWmat code, incorporating advanced corrections for accuracy:
- DFT Framework: Calculations utilized the plane-wave based PWmat code with the Generalized Gradient Approximation (GGA-PBE) functional.
- Pseudopotentials: Optimized norm-conserving Vanderbilt pseudopotentials were employed for structural optimization and electronic state analysis.
- van der Waals Correction: The DFT-D3 method was introduced to accurately model the weak interaction between the h-BN monolayer and the terminated diamond surface.
- Bandgap Calculation: The Hyed-Scuseria-Ernzerhof (HSE06) hybrid functional was used for calculating the bandgaps of the primitive h-BN and diamond cells to ensure accurate electron energy levels.
- Model Construction: Heterostructures were modeled as (2x2) h-BN(001) on (1x1) Diamond(111), using six layers of diamond (H-passivated at the terminal) to reflect bulk properties.
- Convergence Criteria: The plane wave truncation energy was set to 50 Ryd (~680.3 eV). Energy convergence was set to 1 x 10-5 eV·A-3, and the force convergence was set to 0.02 eV/A.
- Strain Application: Biaxial strain (Δ) was applied by changing the lattice constant (L) of the heterostructure, covering a range from -12% (compressive) to 12% (tensile).
- Interface Analysis: Interfacial stability was quantified using the interfacial binding energy (EBE). Charge transfer was analyzed using the charge density difference (CDD) and Hirshfeld algorithm.
Commercial Applications
Section titled âCommercial ApplicationsâThe ability to tune the band structure and band offset of h-BN/diamond heterostructures via mechanical strain opens pathways for next-generation electronic and optoelectronic devices:
- High Power Electronic Devices: Utilizing diamondâs ultra-wide bandgap (UWBG) and high thermal conductivity, these heterostructures are ideal for high-frequency Field Effect Transistors (FETs) and power switching devices.
- Photodetectors and Photocatalysis: Systems with large VBO (e.g., h-BN/H-diamond) are excellent electron acceptors and hole donors, promoting spontaneous and efficient separation of electron-hole pairs, crucial for high-performance photodetectors.
- Tunable Nanoelectronics: The strain-induced semiconductor-to-metal transition observed in h-BN/O-diamond allows for the design of mechanically robust, electrically switchable components and memory devices.
- Surface Conductive Layers: H-terminated diamond interfaces create a highly conductive two-dimensional hole gas (2DHG), which is essential for fabricating low-power Schottky diodes and FETs.
- Efficient Solar Cells: The h-BN/O-diamond system under tensile strain promotes efficient electron-hole recombination, suggesting potential use as an alternative material for improving luminous efficiency in solar cell applications.
View Original Abstract
Abstract The h-BN/diamond mix-dimensional heterostructure has broad application prospects in the fields of optoelectronic devices and power electronic devices. In this paper, the electronic properties and band offsets of hexagonal boron nitride (h-BN)/(H, O, F, OH)-diamond (111) heterostructures were studied by first-principles calculations under biaxial strain. The results show that different terminals could significantly affect the interface binding energy and charge transfer of h-BN/diamond heterostructure. All heterostructures exhibited semiconductor properties. The h-BN/(H, F)-diamond systems were indirect bandgap, while h-BN/(O, OH)-diamond systems were direct bandgap. In addition, the four systems all formed type-II heterostructures, among which h-BN/H-diamond had the largest band offset, indicating that the system was more conducive to the separation of electrons and holes. Under biaxial strain the bandgap values of the h-BN/H-diamond system decreased, and the band type occurred direct-indirect transition. The bandgap of h-BN/(O, F, OH)-diamond system increased linearly in whole range, and the band type only transformed under large strain. On the other hand, biaxial strain could significantly change the band offset of h-BN/diamond heterostructure and promote the application of this heterostructure in different fields. Our work provides theoretical guidance for the regulation of the electrical properties of h-BN/diamond heterostructures by biaxial strain.