We present a detailed first-principles study which explores the configurational space along the relevant reactions and migration paths involving the formation and dissociation of interstitial carbon-oxygen complexes, $\mathrm{C_{i}O_{i}}$ and $\mathrm{C_{i}O_{2i}}$, in silicon. The formation/dissociation mechanisms of $\mathrm{C_{i}O_{i}}$ and $\mathrm{C_{i}O_{2i}}$ are found as occurring via capture/emission of mobile $\mathrm{C_{i}}$ impurities by/from O-complexes anchored to the lattice. The lowest activation energies for dissociation of $\mathrm{C_{i}O_{i}}$ and $\mathrm{C_{i}O_{2i}}$ into smaller moieties are 2.3 eV and 3.1 eV, respectively. The first is compatible with the observed annealing temperature of $\mathrm{C_{i}O_{i}}$ , which occurs at around 400 $^{\circ}$C, and below the threshold for $\mathrm{O_{i}}$ diffusion. The latter exceeds significantly the measured activation energy for the annealing of $\mathrm{C_{i}O_{2i}}$ ($E_{\mathrm{a}}=2.55$ eV). We propose that instead of dissociation, the actual annealing mechanism involves the capture of interstitial oxygen by $\mathrm{C_{i}O_{2i}}$, thus being governed by the migration barrier of $\mathrm{O_{i}}$ ($E_{\mathrm{m}}=2.53$ eV). The study is also accompanied by measurements of hole capture cross sections and capture barriers of $\mathrm{C_{i}O_{i}}$ and $\mathrm{C_{i}O_{2i}}$. In combination with previously reported data, we find thermodynamic donor transitions which are directly comparable to the first-principles results. The two levels exhibit close features, conforming to a model where the electronic character of $\mathrm{C_{i}O_{2i}}$ can be described by that of $\mathrm{C_{i}O_{i}}$ perturbed by a nearby O atom.
A first-principles study of carbon-related energy levels in GaN. Part I - complexes formed by substitutional/interstitial carbons and gallium/nitrogen vacancies
From Mono- to Hexa-Interstitials: Computational Insights into Carbon Defects in Diamond
HUN-REN Wigner Research Centre for Physics（匈牙利科学院维格纳物理研究中心）；Department of Atomic Physics, Institute of Physics, Budapest University of Technology and Economics（布达佩斯技术与经济大学物理研究所原子物理系）；European Laboratory for Learning and Intelligent Systems (ELLIS) Institute Finland（欧洲学习与智能系统实验室芬兰研究所）；Department of Technical Physics, University of Eastern Finland（东芬兰大学技术物理系）；MTA-WFK Lendület “Momentum” Semiconductor Nanostructures Research Group（匈牙利科学院-维格纳物理研究所Lendulet“动量”半导体纳米结构研究组）
Attractive interaction of Indium with point defects and silicon in GeSi
在电子辐照的Ge $_{0.98}$ Si $_{0.02}$中，观察到类似于纯Ge中的缺陷的In空位和In间隙复合物。等时退火测量结果表明，在缺陷复合物的解离温度偏离纯锗进行相同的电子辐照，这是解释的基础上引起的应变过小的硅原子影响的结合能的In-V和In-I复合物。除了与本征缺陷的配对，在与Si原子的相互作用被观察到导致在几个不同的配置。在Ge $_{0.98}$ Si $_{0.02}$和Ge $_{0.94}$ Si $_{0.06}$中进行的补充实验阐明了In和Si之间的吸引相互作用。
Revisiting the configurations of hydrogen impurities in SrTiO3: Insights from first-principles local vibration mode calculations
Advanced Technology Research Institute of Taihu Photon Center, School of Physical Science and Technology, Suzhou University of Science and Technology（太湖光子中心先进技术研究院，苏州科技大学物理科学与技术学院）
研究通过第一性原理局部振动模式计算，重新审视 SrTiO3 中氢杂质的配置及振动特性，发现氢空位复合物与 Sr 空位复合物的振动频率与实验红外吸收带匹配，揭示氢相关复合物对 STO 电子性质的重要性。
Electrical properties of point defects in 4$H$-SiC have been studied extensively, but those related to carbon interstitials (C$_{i}$) have remained surprisingly elusive until now. Indeed, when introduced via ion irradiation or implantation, signatures related to C$_{i}$ observed by deep level transient spectroscopy (DLTS) tend to overlap with those of other primary defects, making the direct identification of C$_{i}$-related levels difficult. Recent literature has suggested to assign the so-called M center, often found in as-irradiated 4H-SiC, to charge state transitions of the C$_{i}$ defect …
Lattice defects affect the long-term stability of halide perovskite solar cells. Whereas simple point defects, i.e., atomic interstitials and vacancies, have been studied in great detail, here we focus on compound defects that are more likely to form under crystal growth conditions, such as compound vacancies or interstitials, and antisites. We identify the most prominent defects in the archetype inorganic perovskite CsPbI$_3$, through first-principles density functional theory (DFT) calculations. We find that under equilibrium conditions at room temperature, the antisite of Pb substituting Cs…
Vacancy-Enhanced $N-N$ Bonding and Deep Level Complex Defect Formation in $β-Ga_2O_3$
International Research Centre Magtop, Institute of Physics Polish Academy of Sciences（波兰科学院物理研究所马格托国际研究中心）；Institute of Plasma Physics and Laser Microfusion（等离子体物理与激光微聚变研究所）；Institute of Fundamental Technological Research Polish Academy of Sciences（波兰科学院基础技术研究所）；Institute of Microelectronics and Optoelectronics, Warsaw University of Technology（华沙理工大学微电子与光电子研究所）；National Center for Nuclear Research（国家核研究中心）；The Centre for Advanced Materials and Technologies, CEZAMAT at the Warsaw University of Technology（华沙理工大学先进材料与技术中心CEZAMAT）
Engineering NV Centers via Hydrogen-Driven Defect Chemistry in CVD Diamonds for Quantum Applications: NVHx Dissociations into NV, Origin of 468nm Center, and Cause of Brown Coloration
In organic solar cells, photogenerated singlet excitons form charge transfer (CT) complexes, which subsequently split into free charge carriers. Here, we consider the contributions of excess energy and molecular quadrupole moments to the charge separation process. We investigate charge photogeneration in two separate bulk heterojunction systems consisting of the polymer donor PTB7-Th and two non-fullerene acceptors, ITIC and h-ITIC. CT state dissociation in these donor-acceptor systems is monitored by charge density decay dynamics obtained from transient absorption experiments. We study the el…
The development of defect populations after proton irradiation of n-type 4H-SiC and subsequent annealing experiments is studied by means of deep level transient (DLTS) and photoluminescence (PL) spectroscopy. A comprehensive model is suggested describing the evolution and interconversion of irradiation-induced point defects during annealing below 1000°C. The model proposes the EH4 and EH5 traps frequently found by DLTS to originate from the (+/0) charge transition level belonging to different configurations of the carbon antisite-carbon vacancy (CAV) complex. Furthermore, we show that the tran…
Neutron bombardments with equivalent fluence (1$\times$10$^{10}$ cm$^{-2}$) and different fluxes ($2.5\times$10$^5$ cm$^{-2}$s$^{-1}$ to $1\times$10$^7$ cm$^{-2}$s$^{-1}$) have been performed on three kinds of bipolar devices with n-type silicon as active regions. The measured increase of base currents and input bias currents are found to decrease with increasing neutron flux, implying that the strength of the dynamic annealing of divacancy defects in n-type silicon follows a positive flux dependence. Such a flux dependence is the same as that observed in ions implantation using protons, but t…
We use hybrid density functional calculations to assess n-type doping in monoclinic (Al$_x$Ga$_{1-x}$)$_2$O$_3$ alloys. We focus on Si, the most promising donor dopant, and study the structural properties, formation energies and charge-state transition levels of its various configurations. We also explore the impact of C and H, which are common impurities in metal-organic chemical vapor deposition (MOCVD). In Ga$_2$O$_3$, Si$_{Ga}$ is an effective shallow donor, but in Al$_2O_3$ Si$_{Al}$ acts as a DX center with a (+/-) transition level in the band gap. Interstitial H acts as a shallow donor …
Spin defects in wide-bandgap semiconductors provide a promising platform to create qubits for quantum technologies. Their synthesis, however, presents considerable challenges, and the mechanisms responsible for their generation or annihilation are poorly understood. Here, we elucidate spin defect formation processes in a binary crystal for a key qubit candidate--the divacancy complex (VV) in silicon carbide (SiC). Using atomistic models, enhanced sampling simulations, and density functional theory calculations, we find that VV formation is a thermally activated process that competes with the c…
The influence of implantation conditions on dopant activation in Al-implanted 4H-SiC: A MD study applying an Al potential fitted to DFT barriers
CDL for Multi-Scale Process Modeling of Semiconductor Devices and Sensors, at the Institute for Microelectronics, TU Wien（维也纳工业大学微电子研究所多尺度半导体器件与传感器工艺建模中心）；Silvaco Europe Ltd.（Silvaco欧洲有限公司）
