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2D metallic materials offer a solution to the problem of poor scalability of elemental metals within ever-downscaling device interconnects. With the absence of surface scattering, they could be used for interconnects in future integrated circuits.

The study of defect centers in silicon has been recently reinvigorated by their potential applications in optical quantum information processing. A number of silicon defect centers emit single photons in the telecommunication $O$-band, making them promising building blocks for quantum networks between computing nodes. The two-carbon G-center, self-interstitial W-center, and spin-$1/2$ T-center are the most intensively studied silicon defect centers, yet despite this, there is no consensus on the precise configurations of defect atoms in these centers, and their electronic structures remain ambiguous. Here we employ \textit{ab initio} density functional theory to characterize these defect centers, providing insight into the relaxed structures, bandstructures, and photoluminescence spectra, which are compared to experimental results. Motivation is provided for how these properties are intimately related to the localization of electronic states in the defect centers. In particular, we present the calculation of the zero-field splitting for the excited triplet state of the G-center defect as the structure is transformed from the A-configuration to the B-configuration, showing a sudden increase in the magnitude of the $D_{zz}$ component of the zero-field splitting tensor. By performing projections onto the local orbital states of the defect, we analyze this transition in terms of the symmetry and bonding character of the G-center defect which sheds light on its potential application as a spin-photon interface., Comment: 11 pages, 6 figures

Although cancer genomes often contain complex genomic rearrangements, its impact on tumorigenesis is still unclear, especially when they are involved in non-coding regions. Understanding 3D genome architecture is crucial for uncovering the impacts of genomic rearrangements. Here, we present InfoHiC, a method for predicting 3D genome folding and cancer Hi-C from complex genomic rearrangements. InfoHiC provides distinct interaction views of multiple contigs from the cancer Hi-C matrix. We then validated cancer Hi-C prediction using breast cancer cell line data and found contig-specific interaction changes. Moreover, we applied InfoHiC to patients with breast cancer and identified neo topologically associating domains and super-enhancer hijacking events associated with oncogenic overexpression and poor survival outcomes. Finally, we applied InfoHiC to pediatric patients with medulloblastoma, and found genomic rearrangements in non-coding regions that caused super-enhancer hijacking events of medulloblastoma driver genes (GFI1, GFI1B, and PRDM6). In summary, InfoHiC can predict genome folding changes in cancer genomes and may reveal therapeutic targets by uncovering the functional impacts of non-coding genomic rearrangements.

A quantitative study on inelastic electron scattering with a molecule is of significant importance for understanding the essential mechanisms of electron-induced gas-phase and surface chemical reactions in their excited electronic states. A key issue to be addressed is the quantitatively detailed inelastic electron collision processes with a realistic molecular target, associated with electron excitation that leads to potential ionization and dissociation reactions of the molecule. Using the real-time time-dependent density functional theory (TDDFT) modeling, we present quantitative findings on the energy transfers and internal excitations for the low energy (up to 270 eV) electron wave packet impact with the molecular target cobalt tricarbonyl nitrosyl (CTN, Co(CO)3NO) that is used as a precursor in electron-enhanced atomic layer deposition (EE-ALD) growth of Co films. Our modeling shows the quantitative dependence of the wave packet sizes, target molecule orientations, and impact parameters on the energy transfer in this inelastic electron scattering process. It is found that the wave packet sizes have little effect on the overall profile of the internal multiple excited states, whereas different target orientations can cause significantly different internal excited states. To evaluate the quantitative prediction capability, the inelastic scattering cross-section of a hydrogen atom is calculated and compared with the experimental data, leading to a constant scaling factor over the whole energy range. The present study demonstrates the remarkable potential of TDDFT for simulating the inelastic electron scattering process, which provides critical information for future exploration of electronic excitations in a wide range of electron-induced chemical reactions in current technological applications.

The excited state quantum dynamics of the organic cation in hybrid perovskites are investigated using the time-dependent density functional theory (TDDFT). The time-dependent non-adiabatic bond fluctuation behaviors reveal that the energy relaxation follows different pathways depending on the chemical bonding characteristics and energy transfer modes within the cation molecule, which can fundamentally affect its photostability. For the ammonium-group-containing cations, such as methylammonium (MA) or ethylammonium (EA), local vibrational modes survive for a long time. However, as their lowest unoccupied molecular orbital (LUMO) having π* characters, the amidinium-group-containing cations, such as formamidinium (FA) or guanidinium (GA), efficiently dissipate deposited energy via chaotic intramolecular vibrational energy redistribution (IVR). The distinct dynamic behaviors of A-site molecular cations are closely related to the quantum ergodicity, which can bring enhanced photochemical stability of FA and GA compared to MA and EA. Our theoretical investigation reveals the quantum chaos origin of better light stability of FA-based perovskites and serves the future research direction of the A-site engineering for better solar cells and light-emitting devices.

Annotation of structural variations (SVs) and base-level karyotyping in cancer cells remains challenging. Here, we present Integrative Framework for Genome Reconstruction (InfoGenomeR)-a graph-based framework that can reconstruct individual SVs into karyotypes based on whole-genome sequencing data, by integrating SVs, total copy number alterations, allele-specific copy numbers, and haplotype information. Using whole-genome sequencing data sets of patients with breast cancer, glioblastoma multiforme, and ovarian cancer, we demonstrate the analytical potential of InfoGenomeR. We identify recurrent derivative chromosomes derived from chromosomes 11 and 17 in breast cancer samples, with homogeneously staining regions for CCND1 and ERBB2, and double minutes and breakage-fusion-bridge cycles in glioblastoma multiforme and ovarian cancer samples, respectively. Moreover, we show that InfoGenomeR can discriminate private and shared SVs between primary and metastatic cancer sites that could contribute to tumour evolution. These findings indicate that InfoGenomeR can guide targeted therapies by unravelling cancer-specific SVs on a genome-wide scale., Karyotyping of cancer genomes at the base-level is technically challenging. Here, the authors introduce InfoGenomeR, an algorithm that can infer cancer genome karyotypes from whole-genome sequencing data, and test their model on breast, ovarian and brain cancer samples; and identify private and shared mutations between primary and metastatic cancer samples.

To investigate inelastic electron scattering, which is ubiquitous in various fields of study, we carry out ab initio study of the real-time dynamics of a one-dimensional electron wave packet scattered by a hydrogen atom using different methods: the exact solution, the solution provided by time-dependent density functional theory (TDDFT), and the solutions given by alternative approaches. This research not only sheds light on inelastic scattering processes but also verifies the capability of TDDFT in describing inelastic electron scattering. We revisit the adiabatic local-density approximation (ALDA) in describing the excitation of the target during the scattering process along with a self-interaction correction and spin-polarized calculations. Our results reveal that the ALDA severely underestimates the energy transferred in the regime of low incident energy particularly for a spin-singlet system. After demonstrating alternative approaches, we propose a hybrid ab initio method to deal with the kinetic correlation alongside TDDFT. This hybrid method would facilitate first-principles studies of systems in which the correlation of a few electrons among many others is of interest.

A new stable current-sourcing transistor is developed using the band-to-band tunneling phenomenon. A heterojunction between thin film WS2 and heavily hole-doped bulk silicon converts a section of the WS2 contacting the silicon into a hole-doped WS2 inside the WS2 channel, and band-to-band tunneling occurs between the electron-doped and hole-doped WS2. The output current is regulated by the tunneling barrier thickness. The thickness depends on the gate bias for device switching, but is less sensitive to the source bias, enabling stable output currents. The minimum line sensitivity is 2.6%, and the temperature coefficient is 1.4 × 103 ppm °C−1. The device can be operated as a current sourcing device with an ultralow output current and power consumption.

The emergent magnetic two-dimensional (2D) materials provide ideal solid-state platforms for a broad range of applications including miniaturized spintronics, nonreciprocal optics, and magnetoelectric sensors. Owing to the general environmental sensitivity of 2D magnets, the understanding of ambient effects on 2D magnetism is critical. Apparently, the nature of itinerant ferromagnetism potentially makes metallic 2D magnets insensitive to environmental disturbance. Nevertheless, our systematic study showed that the Curie temperature of metallic 2D Fe3GeTe2 decreases dramatically in the air but thick Fe3GeTe2 exhibits self-protection. Remarkably, we found the air exposure effectively promotes the formation of multiple magnetic domains in 2D Fe3GeTe2, but not in bulk Fe3GeTe2. Our first-principles calculations support the scenario that substrate-induced roughness and tellurium vacancies boost the interaction of 2D Fe3GeTe2 with the air. Our elucidation of the thickness-dependent air-catalyzed evolution of Curie temperatures and magnetic domains in 2D magnets provides critical insights for chemically decorating and manipulating 2D magnets.

A quantitative study on inelastic electron scattering with a molecule is of significant importance for understanding the essential mechanisms of electron-induced gas-phase and surface chemical reactions in their excited electronic states. A key issue to be addressed is the quantitatively detailed inelastic electron collision processes with a realistic molecular target, associated with electron excitation that leads to potential ionization and dissociation reactions of the molecule. Using the real-time time-dependent density functional theory (TDDFT) modeling, we present quantitative findings on the energy transfers and internal excitations for the low energy (up to 270 eV) electron wave packet impact with the molecular target cobalt tricarbonyl nitrosyl (CTN, Co(CO)

We utilize real-time time-dependent density functional theory and Ehrenfest dynamics scheme to investigate excited-state nonadiabatic dynamics of ligand dissociation of cobalt tricarbonyl nitrosyl, Co(CO)3NO, which is a precursor used for cobalt growth in advanced technologies, where the precursor’s reaction is enhanced by electronic excitation. Based on the first-principles calculations, we demonstrate two dissociation pathways of the NO ligand on the precursor. Detailed electronic structures are further analyzed to provide an insight into dynamics following the electronic excitations. This study sheds light on computational demonstration and underlying mechanism of the electronic-excitation-induced dissociation, especially in molecules with complex chemical bonds such as the Co(CO)3NO.

Hybrid organic-inorganic lead halide perovskites have attracted much attention in the field of optoelectronic devices because of their desirable properties such as high crystallinity, smooth morphology, and well-oriented grains. Recently, it was shown that thermal nanoimprint lithography (NIL) is an effective method not only to directly pattern but also to improve the morphology, crystallinity, and crystallographic orientations of annealed perovskite films. However, the underlining mechanisms behind the positive effects of NIL on perovskite material properties have not been understood. In this work, we study the kinetics of perovskite grain growth with surface energy calculations by first-principles density functional theory (DFT) and reveal that the surface energy-driven preferential grain growth during NIL, which involves multiplex processes of restricted grain growth in the surface-normal direction, abnormal grain growth, crystallographic reorientation, and grain boundary migration, is the enabler of the material quality enhancement. Moreover, we develop an optimized NIL process and prove its effectiveness by employing it in a perovskite light-emitting electrochemical cell (PeLEC) architecture, in which we observe a fourfold enhancement of maximum current efficiency and twofold enhancement of luminance compared to a PeLEC without NIL, reaching a maximum current efficiency of 0.07598 cd/A at 3.5 V and luminance of 1084 cd/m

As the size of the domestic and international gaming industry gradually grows, various games are undergoing rapid development cycles to compete in the current market. However, selecting and recommending suitable games for users continues to be a challenging problem. Although game recommendation systems based on the prior gaming experience of users exist, they are limited owing to the cold start problem. Unlike existing approaches, the current study addressed existing problems by identifying the personality of the user through a personality diagnostic test and mapping the personality to the player type. In addition, an Android app-based prototype was developed that recommends games by mapping tag information about the user’s personality and the game. A set of user experiments were conducted to verify the feasibility of the proposed mapping model and the recommendation prototype.

Background Thymic adenocarcinoma is an extremely rare subtype of thymic epithelial tumors. Due to its rarity, there is currently no sequencing approach for thymic adenocarcinoma. Methods We performed whole exome and transcriptome sequencing on a case of thymic adenocarcinoma and performed subsequent validation using Sanger sequencing. Results The case of thymic adenocarcinoma showed aggressive behaviors with systemic bone metastases. We identified a high incidence of genetic aberrations, which included somatic mutations in RNASEL, PEG10, TNFSF15, TP53, TGFB2, and FAT1. Copy number analysis revealed a complex chromosomal rearrangement of chromosome 8, which resulted in gene fusion between MCM4 and SNTB1 and dramatic amplification of MYC and NDRG1. Focal deletion was detected at human leukocyte antigen (HLA) class II alleles, which was previously observed in thymic epithelial tumors. We further investigated fusion transcripts using RNA-seq data and found an intergenic splicing event between the CTBS and GNG5 transcript. Finally, enrichment analysis using all the variants represented the immune system dysfunction in thymic adenocarcinoma. Conclusion Thymic adenocarcinoma shows highly malignant characteristics with alterations in several cancer-related genes. Electronic supplementary material The online version of this article (doi:10.1186/s12885-017-3282-9) contains supplementary material, which is available to authorized users.

Edge-contacted superconductor-graphene-superconductor Josephson junctions have been utilized to realize topological superconductivity, and have shown superconducting signatures in the quantum Hall regime. We perform first-principles calculations to interpret electronic couplings at the superconductor-graphene edge contacts by investigating various aspects in hybridization of molybdenum $d$ orbitals and graphene \ensuremath{\pi} orbitals. We also reveal that interfacial oxygen defects play an important role in determining the doping type of graphene near the interface.

Fifty-five somatic mutations detected by WES. (DOCX 19Â kb)

Occurrences of the TP53 p.C176F variant in the COSMIC database (version 68). (DOCX 12Â kb)

Enriched KEGG and Reactome pathways (DOCX 14Â kb)

Structural variations detected by FACTERA in the tumor and normal sample. (DOCX 15Â kb)

Two focal SCNAs encompassing less than 10 exons. (A) Focal amplification of the chromosomal region (chr19:9,045,965–9,089,201) detected by Varscan2-CBS. Copy number bins at the region show the significantly-amplified copy number state from the neutral state. The region includes exon 1 to exon 5 of the MUC16 gene. (B) Focal amplification of the chromosomal region (chrX:135,426,776–135,432,395). The amplified region (5 kb) is supported by 26 copy number bins and encompasses exon 6 of the GPR112 gene. (PPTX 239 kb)

Read distributions at each breakpoint of the structural variation between MCM4 and SNTB1. Near exon 8 of MCM4 (chr8:48,877,987–48,879,365), clipped reads support the somatic fusion event between MCM4 and SNTB1 with about 100X coverage. In intron 1 of SNTB1 (chr8:121,815,027–121,815,715), new reads supporting the somatic fusion event are discovered in the tumor sample with about 75X coverage while the intronic region is not covered by WES in the normal sample. (PPTX 171 kb)

Sanger sequencing validation for the mutated six genes. Chromatograms of forward (top) and reverse (bottom) sequences for the normal (left) and tumor (right) sample. (A) 5 SNVs (TGFB2, TP53, TNFSF15, PEG10, and RNASEL) are validated by Sanger sequencing. Base substitutions and allele frequencies from WES are simultaneously represented above results of the validation. Signal intensities of variants detected by Sanger sequencing are consistent with the results of WES. (B) Sanger sequencing confirms the 6-base pair insertion and one-base substitution of FAT1. Detected base shifts derived from the 6-base pair insertion are indicated along the signal. (PPTX 321Â kb)

Five focal SCNAs detected by Varscan2-CBS and EXCAVATOR (DOCX 14Â kb)

The development of high-performance p-type oxides with high hole mobility and a wide bandgap is critical for the applications of metal oxide semiconductors in vertically integrated CMOS devices [Salahuddin et al., Nat. Electron. 1, 442 (2018)]. Sn2+-based oxides such as SnO and K2Sn2O3 have recently been proposed as high-mobility p-type oxides due to their relatively low effective hole masses, which result from delocalized Sn s-orbital character at the valence band edge. Here, we introduce a promising ternary Sn-O-X compound, Ta2SnO6, which exhibits strong valence band dispersion and a large bandgap. In order to evaluate the performance of this oxide as a p-type semiconductor, we perform first-principles calculations of the phonon-limited room-temperature carrier mobilities in SnO, SnO2, and Ta2SnO6. Electron relaxation time is evaluated, accounting for the scatterings from acoustic deformation potentials and polar optical phonons (POP), within the isotropic and dispersionless approximation. At room temperature, the electron/hole mobilities in a given material (SnO, SnO2, and Ta2SnO6) are found to be limited by POP scattering. SnO2 shows high room-temperature electron mobility of 192 cm2/(V s), while SnO and Ta2SnO6 exhibit impressive hole mobilities, with the upper limit at 60 and 33 cm2/(V s), respectively. We find that carrier effective mass largely accounts for the differences in mobility between these oxides with correspondingly different POP scattering rates. The theoretically predicted intrinsic mobilities of each material will provide the upper limit to the real mobilities for their device applications. Our findings also suggest a necessity of further investigation to identify even higher mobility p-type oxides with smaller hole effective masses.

This study focuses on studying the effective electron mobility in direct contact La-silicate/Si structure based nMOSFETs and searching for the difference of the mobility characteristics compared with the SiO 2 MOSFETs. In this study, three types of gate electrode structure were prepared to investigate the mobility characteristics over a wide EOT range; W for EOT of 1.63 nm, TiN/W for EOT of 1.02 nm and metal-inserted poly-Si (MIPS) for EOT of 0.71 nm. Since the silicate formation is basically caused by the presence of oxygen, Si layer in MIPS can suppress the oxygen in-diffusion from atmosphere, resulting in scaled EOT. It is found that the E eff dependence of mobility with La-silicate is observed to differ from the mobility of SiO 2 MOSFETs. The electron mobility with La-silicate shows the weaker E eff dependence than the mobility of SiO 2 nMOSFETs in middle and high E eff region. This suggests an existence of additional mobility component related to the direct contact La-silicate/Si structure. The effective electron mobility is degraded with decreasing EOT in entire E eff region. This means that the scattering sources including Coulomb scattering, phonon scattering and surface roughness scattering are located not at La-silicate/Si interface but the inside of gate stacks and approach the Si inversion channel. Coulomb scattering and phonon scattering are thought to be strengthened by increasing k -value because of the enhancement of Coulomb scattering potential and higher ionicity in La-silicate gate dielectrics. The influence of metal/high- k interface is also considered to affect on the mobility with decreasing the EOT.

We have investigated the noise spectral density of nanowire and planar FETs. It was experimentally found that the nanowire FET shows lower noise density than the planar FET. By a simulation using Poisson-Schrödinger equations, the distribution of inversion carriers is located further from the interface due to quantum confinement, which well explains the observed lower noise density of nanowire FET.

This paper reports on the control of the direct-contact La-silicate/Si interface structure with the aim of achieving scaled equivalent oxide thickness (EOT) and small interface state density. The interface state density at the direct-contact La-silicate/Si interface is found to be reduced to 1.6 × 1011 cm-2eV-1 by annealing at 800 °C for 30 min in forming gas ambient, whereas excess silicate reaction concurrently induced a significant increase in EOT. By utilizing metal-inserted poly-Si (MIPS) stacks and their annealing at high temperature, the increase in EOT is drastically suppressed. At the same time, a superior interfacial property is obtained because the Si layer in the MIPS stacks prevents the excess oxygen diffusion from the atmosphere during the annealing process. As a result, the effective electron mobility of 155 cm2/V·s at 1 MV/cm and an EOT of 0.62 nm are successfully achieved by utilizing direct-contact La-silicate/Si structure. This result is comparable with the recorded effective electron mobility achieved by utilizing Hf-based oxides/Si structure. This demonstrates the advantage of our proposed method to realize the scaled EOT with a superior interfacial property for state-of-the-art metal-oxide-semiconductor field-effect transistors.

To investigate properties of SiNW-FETs, we have studied the band structures of SiNWs aligned to [100] direction with different diameters. Band structures of SiNWs have been derived by first principle calculation. In SiNWs aligned to [100] direction, effective masses of electron are much smaller than those of hole, while numbers of subbands (quantum channels) near the conduction and valance band edge don't have large difference. Those two factors determine the performance for a transistor. Also, inter-band scattering event is more frequent when intervals of subbands are narrower. Then, a trade-off model of the number of quantum channels has been proposed for an optimum diameter extraction.

We have investigated the noise spectral density of nanowire and planar FETs. It was experimentally found that the nanowire FET shows lower noise density than the planar FET. By a simulation using Poisson-Schrodinger equations, the distribution of inversion carriers in the nanowire channel is located further from the interface due to quantum confinement, which well explains the observed lower noise density of nanowire FET.

Oxygen incorporation for compensation of oxygen defects is investigated with La-silicate dielectrics in directly contacted with the Si substrate. The amount of oxygen is controlled by the temperature of annealing in oxygen atmosphere (oxygen annealing) and the thickness of the gate electrode. The positive shift in flatband voltage (VFB) by oxygen incorporation is an experimental evidence for defects compensation in La-silicate dielectrics. Optimum oxygen annealing provides the VFB shift toward positive direction without increasing equivalent oxide thickness (EOT). Although the oxygen annealing degrades the interfacial property at La-silicate/Si interface, subsequent forming gas annealing (FGA) can recover the interfacial property. It is experimentally revealed that the positive VFB shift of La-silicate dielectrics is stable even after subsequent FGA. The supplied oxygen in La-silicate is expected to maintain even after reducing process. Movement of Fermi level toward the Si valence band edge caused by oxygen incorporation is successfully observed by XPS. Moreover, no chemical reaction between La-silicate and Si substrate by oxygen annealing are confirmed from TEM observation and analyses of X-ray photoelectron spectra. It is experimentally demonstrated that effective hole mobility can be improved without increase in EOT by combination of oxygen annealing and FGA.

We fabricated Si nanowire (NW) nFETs, and used them to experimentally demonstrate the superior noise properties of 3D MOSFETs. By carefully comparing the NWFETs with planar FETs, we found that it was critical to control the location of the centroid of the electron density in the inversion channel in order to obtain a noise spectral density with low magnitude. Self-consistent calculations of the Schrodinger and Poisson equations clearly reveal the advantages of NWFETs in electron distribution due to quantum confinement, specifically in the small gate-overdrive (V g -V t ) condition. Moreover, by increasing V d , the range where the NWFET exhibits superior noise properties to a planar FET can be extended to larger V g -V t because the effective V g near the drain is reduced.

This paper reports device process approach for further EOT scaling with small interface state density based on controlling La-silicate/Si interface. The interface state density of 1.6 × 1011 cm−2 eV−1 can be achieved by annealing at 800 °C for 30min in forming gas while significant increase in EOT has been also observed. EOT increase caused by high temperature annealing has been drastically inhibited with MIPS stacks accompanied by high quality interface. The effective electron mobility of 155 cm2/Vsec at 1MV/cm with an EOT of 0.62 nm has been obtained in direct contact La-silicate/Si structure by combination of MIPS stacks with high temperature annealing.

A demonstration of V FB /V th tuning has been conducted by optimized annealing in oxygen ambient for direct contact of high-k with Si gate stacks. The amount of oxygen atoms has been controlled by optimized annealing temperature and the thickness of the gate electrode. The shift in V FB has been confirmed irrespective of gate dielectric materials and the thickness. The V th of pMOSFET can be controlled to positive direction by 520 mV without any EOT penalty. Once a shift in V FB /V th is obtained, the values are found to be stable even after following forming gas annealing.

We carried out a comprehensive study on the impact of size-dependent subband structures on the ballistic silicon nanowire transistors. One of the prominent features was that the injection velocity could be improved, owing to the increase in the source Fermi level measured from the conduction band edge. Moreover, because of the trade-off between the density of states and the gate capacitance, the source Fermi level showed a peak, indicating the optimum wire size for a field-effect transistor. Finally, our results revealed that this trade-off relationship as a feature in nanowire transistors should be considered for the size-dependent performance assessment.