Transferable tight-binding model for strained group IV and III-V materials and heterostructures

Tan, Yaohua; Povolotskyi, Michael; Kubis, Tillmann; Boykin, Timothy B.; Klimeck, Gerhard

doi:10.1103/physrevb.94.045311

Cited by 63 publications

(53 citation statements)

References 43 publications

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“…Foulkes and Haydock showed that the tight-binding approximation emerges as a stationary solution to density functional theory [21], which has provided a solid foundation to improve the accuracy of the tight-binding scheme. Environment-dependent tightbinding models, capturing the essential features of charge transfer and local environmental dependence of overlap integrals (e.g., to reproduce lattice deformations under strain [22]), have further improved the transferability and robustness of the tight-binding approach [18,[23][24][25][26].A key feature of the real-space empirical tight-binding (ETB) approach is its versatility. It can accommodate disorder, strain, magnetic interactions and external perturbations, and, as such, provides a particularly attractive framework to tackle realistic non-equilibrium device conditions in nanosystems and mesoscopic structures [27].…”

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confidence: 99%

KITE: high-performance accurate modelling of electronic structure and response functions of large molecules, disordered crystals and heterostructures

Anđelković

Covaci

et al. 2020

R. Soc. open sci.

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We present KITE, a general purpose open-source tight-binding software for accurate real-space simulations of electronic structure and quantum transport properties of large-scale molecular and condensed systems with tens of billions of atomic orbitals (N ∼ 10 10 ). KITE's core is written in C++, with a versatile Python-based interface, and is fully optimised for shared memory multi-node CPU architectures, thus scalable, efficient and fast. At the core of KITE is a seamless spectral expansion of lattice Green's functions, which enables large-scale calculations of generic target functions with uniform convergence and fine control over energy resolution. Several functionalities are demonstrated, ranging from simulations of local density of states and photo-emission spectroscopy of disordered materials to large-scale computations of optical conductivity tensors and real-space wave-packet propagation in the presence of magneto-static fields and spin-orbit coupling. On-the-fly calculations of real-space Green's functions are carried out with an efficient domain decomposition technique, allowing KITE to achieve nearly ideal linear scaling in its multi-threading performance. Crystalline defects and disorder, including vacancies, adsorbates and charged impurity centers, can be easily set up with KITE's intuitive interface, paving the way to user-friendly large-scale quantum simulations of equilibrium and nonequilibrium properties of molecules, disordered crystals and heterostructures subject to a variety of perturbations and external conditions. arXiv:1910.05194v1 [cond-mat.mes-hall] 11 Oct 2019 2 IntroductionComputational modelling has become an essential tool in both fundamental and applied research that has propelled the discovery of new materials and their translation into practical applications [1]. The study of condensed phases of matter has benefited from significant advances in electronic structure theory and simulation methodologies. Among these advances are: explicitly correlated wave-function-based techniques achieving sub-chemical accuracy [2], first-principles methods to tackling electronic excitations [3], charge-self-consistent atomistic models for accurate electronic structure calculations [4], and the use of machine learning as means to finding density functionals without solving the Khon-Sham equations [5,6].Semi-empirical atomistic methods are amongst the most simple and effective methods to calculate ground-and excited-state properties of materials [7][8][9][10]. The increasingly popular tight-binding approach [11] has been employed for accurate and fast calculations of total energies and electronic structure in complex materials, including semiconductors [12,13], quantum dots [14] and super-lattices [15,16], and is particularly well-suited for implementation of O(N ) (linear scaling) algorithms for efficient calculations of total energies and forces [17].Accurate tight-binding models have been devised for a plethora of model systems, ranging from metals to ionic materials [18], and shown to correctly p...

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confidence: 99%

KITE: high-performance accurate modelling of electronic structure and response functions of large molecules, disordered crystals and heterostructures

Anđelković

Covaci

et al. 2020

R. Soc. open sci.

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“…However, this simple TB model fails to reproduce some important band structure features, such as bandgap nature for indirect semiconductors [3,7]. Although the introduction of additional unphysical parameters can cure the flaw of the simple sp 3 TB model [8][9][10][11], it loses the advantage of its intuitive simplicity and thus is unlikely to uncover the origin of the direct and indirect bandgap natures of semiconductors. The poor understanding impedes the design of new direct bandgap light-emitting materials.…”

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confidence: 99%

“…Here, we reveal that the occupied cation d bands, which were neglected in previous models of the TB approach [6][7][8][9][10][11], play a prime role in forming the direct bandgap of We at first examine the nature of bandgaps of all conventional group-IV elemental, and group III-V and group II-VI compound semiconductors, which are the semiconductors of practical interest for information technology [3,5,23]. Fig.…”

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confidence: 99%

Unified theory of direct or indirect band-gap nature of conventional semiconductors

Yuan

Deng

et al. 2018

Phys. Rev. B

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Although the direct or indirect nature of the bandgap transition is an essential parameter of semiconductors for optoelectronic applications, the understanding why some of the conventional semiconductors have direct or indirect bandgaps remains ambiguous. In this Letter, we revealed that the existence of the occupied cation d bands is a prime element in determining the directness of the bandgap of semiconductors through the s-d and p-d couplings, which push the conduction band energy levels at the X-and L-valley up, but leaves the Γ-valley conduction state unchanged. This unified theory unambiguously explains why Diamond, Si, Ge, and Al-containing group III-V semiconductors, which do not have active occupied d bands, have indirect bandgaps and remaining common semiconductors, except GaP, have direct bandgaps. Besides s-d and p-d couplings, bond length and electronegativity of anions are two remaining factors regulating the energy ordering of the Γ-, X-, and L-valley of the conduction band, and are responsible for the anomalous bandgap behaviors in GaN, GaP, and GaAs that have direct, indirect, and direct bandgaps, respectively, despite the fact that N, P, and As are in ascending order of the atomic number. This understanding will shed light on the design of new direct bandgap light-emitting materials.

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“…assuming linear alloy scaling. The tight‐binding parameters are fitted against bulk DFT calculations using VASP with the HSE06 potentials. The growth direction is the c‐plane and the Wurtzite crystal structure is explicitly represented in this atomistic basis.…”

Section: Methodsmentioning

confidence: 99%

Quantitative Multi‐Scale, Multi‐Physics Quantum Transport Modeling of GaN‐Based Light Emitting Diodes

Geng

Sarangapani

Wang

et al. 2017

Physica Status Solidi (a)

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The performance of nitride‐based light emitting diodes is determined by carrier transport through multi‐quantum‐well structures. These structures divide the device into spatial regions of high carrier density, such as n‐GaN/p‐GaN contacts and InGaN quantum wells, separated by barriers with low carrier density. Wells and barriers are coupled to each other via tunneling and thermionic emission. Understanding of the quantum mechanics‐dominated carrier flow is critical to the design and optimization of light‐emitting diodes (LEDs). In this work a multi‐scale quantum transport model, which treats high densities regions as local charge reservoirs, where each reservoir serves as carrier injector/receptor to the next/previous reservoir is presented. Each region is coupled to its neighbors through coherent quantum transport. The non‐equilibrium Green's function (NEGF) formalism is used to compute the dynamics (states) and the kinetics (filling of states) of the entire device. Electrons are represented in multi‐band tight‐binding Hamiltonians. The I–V characteristics produced from this model agree quantitatively with experimental data. Carrier temperatures are found to be about 60 K above room temperature and the quantum well closest to the p‐side emits the most light, in agreement with experiments. Auger recombination is identified to be a much more significant contributor to the LED efficiency droop than carrier leakage.

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Transferable tight-binding model for strained group IV and III-V materials and heterostructures

Cited by 63 publications

References 43 publications

KITE: high-performance accurate modelling of electronic structure and response functions of large molecules, disordered crystals and heterostructures

KITE: high-performance accurate modelling of electronic structure and response functions of large molecules, disordered crystals and heterostructures

Unified theory of direct or indirect band-gap nature of conventional semiconductors

Quantitative Multi‐Scale, Multi‐Physics Quantum Transport Modeling of GaN‐Based Light Emitting Diodes

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