Substitutional Doping Research Articles

Regulating Chemical Bonds in Halide Frameworks for Lithium Superionic Conductors.

Developing solid-state electrolytes (SSEs) is a critical task for advancing all-solid-state batteries (ASSBs) that promise a high energy density and improved safety. The dominant strategy in engineering advanced SSEs has been substitutional doping, where foreign atoms are introduced into the atomic lattice of a host material to enhance ionic conduction. This enhancement is typically attributed to optimized charge carriers' concentration or lattice structure alterations. In this study, we extend the concept of substitutional doping to explore its effects on chemical bond modulation and the resulting impact on ionic conduction in halide SSEs. As a case of study, we demonstrate that cation dopants with high charge density indices (e.g., Al3+ and Fe3+) can increase the covalency of metal-halide (M-X) bonds and induce the local asymmetric field of force, resulting in higher site energy and lower migration barriers, which significantly enhance the ionic conduction in halide frameworks. Specifically, we developed a series of halide SSEs with ionic conductivities exceeding the benchmark value of 1 mS cm-1 at room temperature. Detailed investigations, including neutron powder diffraction, pair distribution function analysis, and first-principles calculations, are performed to gain an insight into the mechanisms behind this adjustment. Furthermore, these materials exhibit enhanced deformability due to increased covalency of the metal halide framework, enabling high-performance ASSB prototypes operatable at low stacking pressures (<10 MPa). These advancements deepen our understanding of superionic conduction in halide SSEs and mark an important step toward the practical application of ASSBs in the future.

Theoretical Investigations on the n-Type and p-Type Conductivity Mechanisms in BiTaO4 Photocatalysts through Intrinsic Point Defects and Group IIA and Group VIB Element Doping.

The n-type and p-type conductivity mechanisms from intrinsic defects and Group IIA and Group VIB element doping in the photocatalyst BiTaO4 are systematically investigated by employing hybrid density functional calculations. The results reveal that vacancies VBi, VTa, VO, and antisite TaBi are the predominant defects, depending on growth conditions. Bi-rich, appropriate Ta-rich, and O-poor conditions can promote BiTaO4 to form n-type conductivity due to the presence of the TaBi donor defect and its easier ionization. This explains the experimental n-type conductivity character well. Meanwhile, under O-rich, Bi-poor, and Ta-poor conditions, BiTaO4 exhibits superior p-type conductivity by forming the excellent acceptor defects VBi and VTa. Moreover, the intrinsic p-type conductivity can be further strengthened via the introductions of the substitutional doping of MBi (M = Mg, Ca, Sr, and Ba) under the Bi-poor, Ta-poor, and O-rich conditions, where the O vacancies should be induced and Sr is the best candidate. On the other hand, Group VIB element (Cr, Mo, and W) doping can improve intrinsic n-type conductivity under Bi-rich, appropriate Ta-rich, and O-poor conditions. W is the best candidate. These findings provide a comprehensive understanding of defect physics in BiTaO4 and offer insights into optimizing its photocatalytic performance through targeted defect engineering and impurity doping.

Modulating room-temperature phosphorescence of D-π-A luminogens via methyl substitution, positional isomerism, and host-guest doping.

Organic room-temperature phosphorescence (RTP) luminogens have showed significant potential in the fields of diagnostics, sensing, and information encryption. However, it is difficult to achieve high RTP yield (ΦP) and long RTP lifetime simultaneously. By methyl substitution, positional isomerism, and host-guest doping, three new D-π-A type luminogens named as TBTDA, 2M-TBTDA, and 3M-TBTDA were designed and synthesized, whose RTP properties were tuned and optimized. In various solvents and glassy THF solution, similar solvatochromism and phosphorescence nature of three luminogens were revealed. In poly (methyl methacrylate) (PMMA) and polyvinyl alcohol (PVA) matrixes, the luminogens showed high-contrast RTP properties. TBTDA emitted invisible afterglow in PMMA films, but with strong RTP and long green afterglow in PVA films. More importantly, 2M-TBTDA showed RTP and afterglow lifetimes of 809.81ms and 8s, as well as ΦP of up to 0.64 in PMMA at 1% doping concentration. Taking advantage of Foerster resonant energy transfer (FRET), reddish-brown or orange afterglow were observed, with emission maxima of 593-617nm, RTP and afterglow lifetimes of 299-566ms and 5-6s, ΦP of 0.34-0.46, as well as FRET efficiency of 70-90%. Finally, dynamic anti-counterfeiting and digital encryption were successfully constructed via different fluorescence, RTP colors, and afterglow lifetimes. This work not only obtained an efficient host-guest doping RTP system, but also can be expected to provide more theoretical guidance and experimental supports for molecular design, dynamic anti-counterfeiting and digital encryption.

The Influence of Mg Doping in α-Al2O3 Crystals Investigated with First-Principles Calculations and Experiment.

The influence of Mg doping in α-Al2O3 crystals is investigated in this article by first-principles calculations and formation energies, density of states, and computed absorption spectra. Three models related to Mg2+ substituting for Al3+ doping structures were constructed, as well as spinel structure models with varying aluminum-magnesium ratios. The formation energy calculations confirmed the rationality of the MgAlVO model, which means that Mg substitutional doping incorporating oxygen vacancies is most likely to form in crystals. The combined action of magnesium and oxygen vacancies introduced new defect energy levels in the bandgap. The calculated absorption spectra of the MgAlVO and Mg-rich spinel structures exhibited various color centers. The experimental absorption spectra and thermoluminescence characteristics of α-Al2O3:Mg and alumina-magnesium (Al-Mg) spinel crystal samples were tested. The thermoluminescence peak of the Al-Mg spinel was significantly stronger than that of the α-Al2O3:Mg crystal. The consistency between the model-calculated absorption spectra and the experimental results confirmed the theoretical predictions. Based on the experimental and computational results, the influence of Mg2+ substitutional doping in α-Al2O3 and the impact of the locally Mg-rich spinel on the optical and radiation performance of α-Al2O3:Mg crystals are elucidated.

Physical properties of Mo2C monolayer by substitutional doping with Co/Cu atoms

Physical properties of Mo2C monolayer by substitutional doping with Co/Cu atoms

Ionic Liquid Mediated Sol Gel Method for Fabrication of Nanostructured Cerium and Phosphorus Doped TiO2 - A Benign Photocatalyst: Diversified Applications in Degradation of Dyes and Microbes.

This work aims to produce semiconductor nanoparticles capable of harnessing visible light for the degradation of dyes and microbes. Employing an ionic liquid-assisted sol-gel process with varying dopant weight percentages, the study focuses on crafting Cerium (Ce) and Phosphorus (P) doped TiO2 Nanomaterials. Structural assessments, including Powder X-ray Diffraction (confirming the anatase phase), Transmission Electron Microscopy (revealing a particle size of 6.2 nm), Brunauer-Emmett-Teller surface area analysis (yielding 166 m2/gr), and Scanning Electron Microscopy (examining the morphology), were conducted. The catalysts were further evaluated for optical characteristics: UV-vis diffuse reflectance spectrum (indicating an energy gap of 2.59 eV), Electrochemical Impedance Spectroscopy (with an Efb of -0.30 V), and Valence band XPS (showing Evb at 2.03 eV). Substitutional doping of dopants into the TiO2 lattice was confirmed through X-ray photoelectron spectroscopy and Fourier Transform Infra-Red analysis. Photoluminescence Spectrum and Time Correlated Single Photon Counting analysis was employed to investigate electron-hole recombination. These characterizations suggest the catalysts are effective in degrading microorganisms and dyes under visible light exposure. Optimal conditions were obtained using CPT5IL2 at pH 3, 0.10 g catalyst dosage, and an initial dye concentration of 10 mg/L, which were determined to achieve complete dye degradation within 60 min. Furthermore, the catalyst's antibacterial and antifungal activity against Enterobacter aerogenes (MTCC-241, Gram-negative), Salmonella typhimurium (MTCC-98, Gram-negative), and Candida albicans (MTCC-277) were studied.

Unveiling Substitutional Doping Strategy of Non-Metals in 2D Holey Graphyne for Computational Design of Efficient catalyst for Hydrogen Evolution Reaction

Unveiling Substitutional Doping Strategy of Non-Metals in 2D Holey Graphyne for Computational Design of Efficient catalyst for Hydrogen Evolution Reaction

Demonstrating the substitutional doping of erbium (Er) in BiFeO3 nanoparticles for the enhanced solar-driven photocatalytic activity

Demonstrating the substitutional doping of erbium (Er) in BiFeO3 nanoparticles for the enhanced solar-driven photocatalytic activity

Effects of Doping on Elastic Strain in Crystalline Ge-Sb-Te.

Phase-change random access memory (PcRAM) faces significant challenges due to the inherent instability of amorphous Ge2Sb2Te5 (GST). While doping has emerged as an effective method for amorphous stabilization, understanding the precise mechanisms of structural modification and their impact on material stability remains a critical challenge. This study provides a comprehensive investigation of elastic strain and stress in crystalline lattices induced by various dopants (C, N, and Al) through systematic measurements of film thickness changes during crystallization. Through detailed analysis of cross-sectional electron microscopy data and theoretical calculations, we reveal distinct behavior patterns between interstitial and substitutional dopants. Interstitial dopants (C and N) generate substantial elastic strain energy (~9 J/g) due to their smaller atomic radii (0.07-0.08 nm) and ability to occupy spaces between lattice sites. In contrast, substitutional dopants (Al) produce lower strain energy (~5 J/g) due to their similar atomic radius (0.14 nm) to host atoms. We demonstrate that N doping achieves higher elastic strain energy compared to C doping, attributed to its preferential formation of Ge-N bonds and resulting lattice distortions. The correlation between dopant properties, structural features, and induced strain energy provides quantitative insights for optimizing dopant selection. These findings establish a fundamental framework for understanding dopant-induced thermodynamic stabilization in GST materials, offering practical guidelines for enhancing the reliability and performance of next-generation PcRAM devices.

Exploring Intrinsic and Extrinsic p-Type Dopability of Atomically Thin β-TeO2 from First Principles.

Two-dimensional (2D) β-TeO2 has gained attention as a promising material for optoelectronic and power device applications, thanks to its transparency and high hole mobility. However, the mechanisms driving its p-type conductivity and dopability remain elusive. In this study, we investigate the intrinsic and extrinsic point defects in monolayer and bilayer β-TeO2, the latter of which has been experimentally synthesized, using the Heyd-Scuseria-Ernzerhof (HSE) + D3 hybrid functional. Our results reveal that most intrinsic defects are unlikely to contribute to p-type doping in 2D β-TeO2. Moreover, Si and H contamination could further impair p-type conductivity. Since the point defects do not contribute to p-type conductivity, we suggest two possible mechanisms for hole conduction: hopping conduction via localized impurity states, and substrate effects. We also explored substitutional p-type doping in 2D β-TeO2 with 10 trivalent elements. Among these, the Bi dopant is found to exhibit a relatively shallow acceptor transition level. However, all the dopants introduce deep localized states, where hole polarons are trapped by the lone pairs of Te atoms. Interestingly, monolayer β-TeO2 shows potential advantages over bilayers due to reduced self-compensation effects for p-type dopants. These findings provide valuable insights into defect engineering strategies for future electronic applications involving 2D β-TeO2.

Engineering of Metal-Organic Framework-Derived CoTiO3 Micro-Prisms for Lithium-Ion Batteries.

Metal-organic framework (MOF)-derived transition metal compounds and their composites have attracted great interest for applications in energy conversion and storage. In this work, hexagonal micro-prisms of Ni-doped CoTiO3 composited with amorphous carbon (NixCTO/C) were synthesized using Ti-Co-based MOFs as precursors. The experimental results indicate the substitutional doping of Ni2+ for Co2+ in CoTiO3 (CTO), leading to improved conductivity, as further confirmed by density functional theory calculations. Thus, the carbon-free sample of Ni-doped CTO exhibits improved lithium storage properties compared to the pristine one. Furthermore, when coupled with in situ-formed carbon, the dually modified Ni0.05CTO/C micro-prisms demonstrated a significantly increased reversible capacity of 584.8 mA h g-1, excellent rate capability, and superior cycling stability at a high current density of 500 mA g-1. This enhanced electrochemical performance can be attributed to the synergistic effect of Ni doping and carbon coating.

Optimization of Thermoelectric Performance in p-Type SnSe Crystals Through Localized Lattice Distortions and Band Convergence.

Crystalline thermoelectric materials, especially SnSe crystals, have emerged as promising candidates for power generation and electronic cooling. In this study, significant enhancement in ZT is achieved through the combined effects of lattice distortions and band convergence in multiple electronic valence bands. Density functional theory (DFT) calculations demonstrate that cation vacancies together with Pb substitutional doping promote the band convergence and increase the density of states (DOS) near the Fermi surface of SnSe, leading to a notable increase in the Seebeck coefficient (S). The complex defects formed by Sn vacancies and Pb doping not only boost the Seebeck coefficient but also optimize carrier concentration (nH) and enhance electrical conductivity (σ), resulting in a higher power factor (PF). Furthermore, the localized lattice distortions induced by these defects increase phonon scattering, significantly reducing lattice thermal conductivity (κlat) to as low as 0.29Wm-1K-1at 773K in Sn0.92Pb0.03Se. Consequently, these synergistic effects on phonon and electron transport contribute to a high ZT of 1.8. This study provides a framework for rational design of high-performance thermoelectric materials based on first-principles insights and experimental validation.

Enabling room-temperature ferromagnetism and p-type conductance in MoS 2 monolayers by substitutional doping of vanadium

Enabling room-temperature ferromagnetism and p-type conductance in MoS ₂ monolayers by substitutional doping of vanadium

Study on the mechanism of enhancing photocurrent in TiS2 photodetector by vacancy- and substitution-doping

In materials lacking spatial inversion symmetry, the photovoltaic generation effect (PGE) manifests under polarized irradiation without the necessity of a p-n junction and demonstrates high polarization sensitivity across a broad spectrum. This characteristic presents significant potential for applications in low-power two-dimensional optoelectronic devices. In this study, we investigate the electronic structure, optical properties, and PGE in 2H-TiS2 by first-principles simulations, incorporating various types of point defects. We propose a mechanism to enhance photoconductivity in 2H-TiS2 by substitution doping and vacancy defects. When the photodetector is aligned along the armchair direction, the photocurrent exhibits a cosine dependency on the linear polarization angle. We achieved a remarkable enhancement in photocurrent, with a maximum value of 1.33 a20/photon, in contrast to only 0.11 a20/photon for the pure membrane. This improvement can be attributed to the introduction of point defects, which diminish the symmetry of the device and increase its asymmetry, thereby enhancing the photocurrent. Furthermore, we attained high polarization sensitivity, evidenced by a maximum extinction ratio of 262.4. Our findings not only propose an effective mechanism for enhancing PGE by substitution doping but also underscore the promising applications of the two-dimensional 2H-TiS2 monolayer in optoelectronics, particularly in photoelectric detection.

Single Rh atom substitution doping in NiS2 monolayer for density functional theory designing as a promising adsorbent or sensor upon N-containing gases

This study from the insight of density functional theory (DFT) purposes the single Rh atom substitution doping in NiS2 (Rh-NiS2) monolayer to be a potential gas adsorbent or sensor upon three N-containing gases, namely NO, NO2 and NH3. A S atom is substituted by a Rh atom in the pristine surface to establish the purposed monolayer, which is a energy-favorable process with a formation energy of −0.52 eV. The Rh-NiS2 monolayer conducts chemisorption upon three gas species, with a binding strength orderly as NO > NO2 > NH3. The Hirshfeld analysis elucidates the electron-donating property of NO and NH3 molecules and the electron-accepting nature of the NO2 molecule during their interactions with the monolayer, as evidenced by the charge density difference. The band structure and density of stats of the Rh-NiS2 monolayer for gas adsorption as well as the monolayer’s recovery property for gas desorption are fully analyzed to explore its potential applications. The findings indicate the potential of Rh-NiS2 monolayer as an effective gas adsorbent for the capture and removal of NO and NO2 gases, and as a promising resistive gas sensor for repeated NH3 sensing without a compromise in sensitivity. Moreover, the Rh-NiS2 monolayer can also be applied for selective detection or gas separation between NH3 and NOx (x = 1 or 2) owing to the significant disparity in their sensing responses. These insights guide the development of NiS2-based gas adsorbent and sensor that can accurately detect N-containing gases for environmental monitoring, industrial safety, and other applications.

Synergistic effects of interstitial and substitutional doping on the thermoelectric properties of PbS

Lead sulfide (PbS) is widely recognized as a promising n-type thermoelectric material for use in the middle-temperature range. Although it already exhibits favorable electronic and thermal properties, its thermoelectric performance could be further enhanced by addressing the disparity between the light and heavy bands in the conduction band, thereby optimizing electrical transport, and by modifying the strength of its chemical bonds to reduce lattice thermal conductivity. In this study, we demonstrate that introducing just small amounts of antimony (Sb) into PbS generates a unique combination of interstitial and substitutional doping that leads to a significant improvement in both directions. Substitutional doping enhances the degeneracy between the light and heavy bands, increasing carrier mobility. At the same time, interstitial doping introduces a new resonance state near the Fermi level, providing an additional channel for electron transport while boosting carrier concentration. These synergistic effects lead to a marked increase in the power factor of PbS, achieving an average power factor (PFavg) of 1.07 mW m−1 K−2 across the temperature range of 320–873 K. Moreover, Sb substitution for Pb induces a shift in the surrounding S atoms toward Sb, weakening their bonds with neighboring Pb atoms. This shift results in a coexistence of strong and weak chemical bonds, which effectively reduces lattice thermal conductivity. Additionally, the defect structures introduced by Sb doping effectively scatter phonons, further lowering lattice thermal conductivity. As a result, PbS doped with 0.5% Sb exhibits a figure of merit (ZT) of 0.73 at 873 K, which is approximately three times higher than that of undoped PbS.

(Invited) Unveiling Olivine Cathodes for High-Energy-Density Lithium-Ion Batteries: Engineering from the Atomic Level to the Electrode Scale

The pursuit of high energy density has spurred significant interest in layered cathodes such as lithium nickel cobalt manganese oxide (NCM) or lithium nickel cobalt aluminium oxide (NCA), renowned for their excellent energy storage capabilities. However, Ni- and Co-based layered cathodes face significant thermal instability, resulting in thermal runaway in the case of short circuits, high temperature exposure, and so forth. Recently, lithium iron phosphate (LFP) has emerged as an alternative due to its enhanced structural and thermal stability, despite the absence of expensive metals such as Co and Ni. However, LFP encounters significant challenges, notably its inherently low redox potential and capacity (energy density), which undermines its competitiveness in electric device applications such as electric vehicles (EVs) and energy storage systems (ESSs). Boosting energy density can now be accomplished through the engineering of active materials and electrode configurations. It has been noticed that new strategies, such as increasing the working voltage through fine-tuning of active materials and/or using thick electrodes to augment the ratio of active materials per unit area, can make a breakthrough for elevating energy density within the existing battery volume dimension. However, transitioning to thick electrodes poses challenges related to electron and ionic conductivity, as well as the structural stability of the electrode.Herein, I will present integrating strategies for enhancing the high-energy density of olivine cathodes. This includes atomic modifications such as substitutional doping with manganese to achieve a high redox voltage, and particle/electrode engineering techniques like optimizing tap and press density. In addition, I will briefly show key technologies involving conducting agents and binders used to construct thick electrodes for olivine cathodes through eco-friendly processes. A comprehensive understanding will provide insights into how to conduct research on olivine-based cathodes and contribute to the impacts of secondary batteries in both academia and industry.

VOC Detection Using p-Type Sm(Fe,Co)O3 Perovskite Oxides

In recent years, there has been concern about the resurgence of sick house syndrome caused by volatile organic compounds (VOCs) emitted from building materials, and there is an urgent need to develop sensors that can continuously detect VOCs with high sensitivity. Our research group is conducting research on VOC detection characteristics using SmFeO3. SmFeO3 is a p-type semiconductor with a perovskite crystal structure and has high oxidation activity against VOCs. However, SmFeO3 has high electrical resistance in air, and sensors using SmFeO3 require heating to a measurable resistance range (approximately 300°C or higher), and also require a measurement system with high input impedance. For this reason, a high cost for apparatus and high power consumption are issues for practical application. Therefore, in this study, we focused on SmFe1-xCoxO3 as the sensing electrode material to operate sensors at reduced temperature. Since SmFeO3 is a p-type semiconductor, Co substitution or hole doping is expected to increase electrical conductivity, and a good redox property of cobalt ion may enhance catalytic activity of VOC decomposition. Regarding the oxidation activity of SmFe1-xCoxO3 powder, the oxidation activity against toluene increased with increasing Co content. T50 = 210oC (x=0), 205 oC (x=0.1), 155 oC (x=0.3), 165 oC (x=0.5). The oxidation activity for ethanol also increased with the amount of substitution, T50 =130oC (x=0), 110 oC (x=0.1), 85 oC (x=0.3), 75 oC (x=0.5). The temperature at which the maximum response value of each sensor was shown is 300℃ (x=0), 250℃ (x=0.1), 250℃(x=0.3), and 200oC (x=0.5). It was found that the Co substitution effectively reduce operating temperature. The response value (RVOC/Rair) in ethanol was results in S=4.6 (x=0 at 300oC), S=6.4 (x=0.1 at 250oC) and the sensor with x=0.1 increased sensor response at reduced temperature. The increase in the response value is thought to be because the sensor with x=0.1 has a higher oxidation activity at 250 oC than that with x=0 at 300 oC, The response of the sensors followed the power law, S=aPVOC n. Here, a and n are constants, and PVOC is the partial pressure of the gas. The constants a and n were determined from the equation log(S)=log(a)+nlog(PVOC), and the response value to 0.1 ppm ethanol was predicted as S=1.11 (x=0), 1.88 (x=0.1), 1.88 (x=0.3), and 1.94 (x=0.5), and it was expected that the response values at 0.1 ppm would increase due to cobalt substitution. Sensor properties mainly depend on material properties and sensor structure (sensing membrane structure). Therefore, it is suggested that higher sensitivity can be achieved by optimizing the sensor structure in the future, and it is considered that the use of cobalt substitutes as a sensor material is useful from the viewpoint of sensitivity.

(Invited) Applications of Oxygen Inserted Epitaxy

Silicon remains the semiconductor material of choice for most electronic applications of semiconductors and the silicon–silicon dioxide interface is one of the most studied interfaces. Over the past decade or more, epitaxial silicon-germanium (eSiGe) has found increasing applications in advanced logic, first for PMOS compressive source-drain (S/D) stressors, then as a channel material in high-k metal gate (HKMG) devices to help control the PMOS Vt, and more recently as a sacrificial layer to enable stacked nanosheets and even as a S/D liner to reduce phosphorus diffusion into the undoped nanosheets. Oxygen inserted (OI) silicon epitaxy was originally developed to complement and bridge the gap between silicon and silicon-germanium, and it has found applications ranging from improved figure of merit power devices to the most advanced nanosheet applications. In this paper we will provide an overview of OI silicon devices, their fundamental characterization and the electrical and physical benefits offered for a variety of semiconductor applications. Introduction Oxygen-inserted (OI) silicon had an unusual genesis for a semiconductor material, in that it was first explored using ab-initio quantum mechanical simulation. It was found that by carefully inserting a partial monolayer of oxygen during silicon epitaxy a stable layer could be manufactured where the individual oxygen atoms arranged themselves on a silicon-silicon bond, but that overall, the silicon retained its regular lattice, and the silicon-oxygen coordination was only one, as opposed to four in regular silicon dioxide. The idealized lattice configuration is shown in Fig. 1 (a). This configuration is technically thermodynamically metastable, but with a significant energetic barrier to formation of four-fold coordinated silicon dioxide, so that it can survive conventional semiconductor processing. Whereas a single oxygen atom is known to rapidly diffuse in silicon, there is a thermodynamic self-stabilization when the oxygen concentration has an aerial density of the order of 1E15cm-2, with an upper limit dependent both on the specific epitaxial recipe and the required defect density. If all available silicon bonds have attached oxygen, it is difficult to maintain high quality epitaxy. On the other hand, OI silicon has passed the most rigorous defect density requirements for advanced logic applications. Dopant engineering - simulation Oxygen is highly electronegative, and ab initio simulation shows that there is charge transfer in the silicon lattice in the near vicinity of the inserted oxygen as shown in Fig 1 (b). This leads to a change in the formation enthalpy for a single substitutional dopant atom or addition of a silicon point defect, vacancy or interstitial as shown in Fig 1 (c). The figure indicates that substitutional boron and phosphorus will have an energetic preference to be two or three silicon lattice atoms away from the inserted oxygen, whereas silicon point defects prefer to be coincident with the oxygen. As a result, the OI layers disrupt the diffusion of dopant-interstitial pairs, substantially reducing the dopant diffusion. Dopant engineering – experimental data OI silicon has been proven to create unique abrupt doping profiles for a variety of silicon and silicon germanium devices. In power devices, reducing the vertical and lateral diffusion below the OI silicon layer can be used to engineer significant improvement in critical figures of merit, such as the tradeoff between specific ON resistance (Rsp) and the breakdown voltage, and improved time constant (Ron∙ Coff) and reduced body current in RF power devices, while maintaining breakdown voltage. In advanced 3D applications, a 2nm thin liner of OI silicon has proven effective to create a diffusion barrier between highly doped epitaxial source/drain regions and undoped channels. By reducing dopant up-diffusion, thermally robust super-steep retrograde profiles can be created, which can be used to reduce local threshold voltage mismatch in both NMOS and PMOS devices by more than 50%. In gate-first HKMG planar CMOS applications, SiGe channel is used in the PMOS to facilitate Vt engineering. A thin OI silicon layer below the SiGe channel can be used to maintain a super-steep retrograde channel profile after HKMG formation and subsequent thermal processing. Interface interactions It has recently been discovered that OI silicon can also be used to engineer adjacent interfaces. For example, it has been shown by cryogenic measurements that OI silicon reduces surface roughness scattering of the silicon-dielectric interface. Also, OI silicon can reduce the interfacial dipole formed during HKMG processing, with benefits in reduced remote charge scattering and improved reliability.These and other examples of engineered silicon and silicon-germanium devices will be discussed in detail. Figure 1

Boosting hydrogen storage performance in COF-108 by single-walled carbon nanotube insertion, boron substitution, and lithium doping at room temperature

Boosting hydrogen storage performance in COF-108 by single-walled carbon nanotube insertion, boron substitution, and lithium doping at room temperature