(AlxGa1−x)2O3 is a novel ultra-wide bandgap semiconductor with the potential to dominate future power electronics industries. High-performance devices demand high Al content in (AlxGa1−x)2O3 but are limited by crystallinity degradation resulting from phase separation. Additionally, the solubility limit of Al is still under debate, and conclusive research is in progress. (AlxGa1−x)2O3 is also limited in high-frequency applications owing to low carrier mobility and requires n-type doping. For commercializing this material, the major obstacle is understanding dopant's behavior in the host (AlxGa1−x)2O3. To investigate these issues, an advanced characterization technique, atom probe tomography (APT), was employed to analyze the structural-chemical evolution of (AlxGa1−x)2O3. In this review, we summarized our recent works on the structure-chemistry investigation of (AlxGa1−x)2O3 with alloy composition and doping interaction. We introduced machine learning algorithms on APT data to reveal unrivaled knowledge, previously not achievable with conventional methodologies. The outstanding capabilities of APT to study (AlxGa1−x)2O3 with Al composition and doping will be considered significant for the wide bandgap semiconductors community.

A new series of ternary perovskite 0.975(0.8Bi1/2Na1/2TiO3–0.2Bi1/2K1/2TiO3)–0.025Bix/3Mgy/3Nbz/3O3 (BNT–BKT–BMN, BMN-xyz) ceramics were designed and synthesized. The effect of the element ratio in the doping component BMN on the strain, ferroelectric, piezoelectric, and dielectric properties of the BNT–BKT matrix were studied. The BMN-430 composition without Nb element exhibits the typical features of non-ergodic relaxor, which is characterized by a higher piezoelectric coefficient d33 and a butterfly-shaped strain curve with negative strain. The introduction of trace Nb can significantly enhance the ergodicity of the system, reflecting in the high positive strain response and strain coefficient $\lpar {d_{33}^\ast \gt 750\;{\rm pm/V}} \rpar$ of BMN-321 composition. In contrast, there is no significant difference in the properties between the presence and absence of Mg element. The temperature-dependent electrical behaviors of BMN-xyz ceramics were analyzed based on impedance spectroscopy. This study may be helpful to the design of the chemical modification strategy for the BNT-based relaxor ferroelectrics.

Piezoelectric Ba0.85Ca0.15Zr0.1Ti0.9O3 (BCZT) has been found to be a competitive lead-free piezoceramic candidate and was prepared by a sol–gel technique due to its small particle size and homogeneous particle size distribution, but the sintering temperature is still quite high in the previous reports. In the present paper, lithium carbonate (Li2CO3) was used as a sintering aid and dopant for the sol–gel-derived piezoceramic powder, to facilitate the sintering process and adjust the densification, the microstructures and functional properties. With the addition of 0.5 wt% Li2CO3 sintered at 1300 °C, a high relative density 96% with piezoelectric coefficient d33 ~447 pC/N, planar coupling coefficient kp ~0.51, and Curie point TC ~98.7 °C was obtained. The way to properly define the critical changing points on temperature-dependent dielectric curves were further discussed. By altering sintering temperature and the amount of dopant, the mutual influence between the microstructures and the functional properties was explained, to further guide shaping BCZT in more complexed connectivities.

In this paper, we report a recent theoretical study of the calculation of the binding energy and photoionization cross section of a single dopant in a spherical hollow or core/shell quantum dot taking into account the interaction of the electron with longitudinal optical phonons. Using Frolich approach and Lee-low Pines transformation, we determine the impact of different parameters such as shell thickness and dopant position on the energy and optical response of a bound polaron for two types of ionic II–VI semiconductors CdTe and ZnSe with different phonon coupling constants. Regardless of the material used, the electron–phonon interaction visibly reduces binding energy. For photoionization cross section, a redshift of resonance peaks was found when the effect of phonons is taken into consideration or when the donor is moved away from the shell center. These calculations provide us insights when choosing between materials for optoelectronic applications.

The study report on Vanadium dioxide thin films of about 100nm thickness deposited using pulsed laser deposition on Si (100). The novel phase change reported is attributed to the post-treatment of the films via ion implantation with 25 KeV C+ ion beam at varying particle fluence (1E15, 1E16, and 1E17 /cm2). At the initial fluence, the preferred phase is retained while amorphization and recrystallization of the film is observed as the fluence increase to 1E16 ions/cm2and 1E17 ions/cm2, respectively. The phase transition of the samples is observed to occur at a temperature below 320 K while stabilization of the low phase structure is observed for the middle fluence. Further increase restores the SMT behaviour/trend that occurred at elevated temperatures.

A scalable preparation of in situ N-doped disordered carbon nanosheets from reduced melamine formaldehyde resin is demonstrated. For the first time, nanosheets prepared by such a process have been tested as anodes for lithium ion and sodium ion batteries. Li-ion battery half-cell delivers a reversible capacity of about 500 mA h/g at a specific current of 100 mA/g, and also a capacity of 250 mA h/g at a specific current of 500 mA/g is retained after 600 cycles. For Na-ion batteries, a reasonable capacity of about 150 mA h/g is recorded at a specific current of 50 mA/g, and a capacity of 120 mA h/g at a specific current of 250 mA/g is retained after 350 cycles. The sloppy low-voltage profile obtained for both the lithium ion and sodium ion cells corresponds to the nanosheet anodes, being soft carbon-like, thereby demonstrating superior cycling stability and safety by avoiding metal plating and dendrite formation.

In this work, a multifunctional system was developed in which antibacterial and luminescent properties were inserted into the matrix of hydroxyapatite (HAp) and its efficiency as a support for an antineoplastic drug was evaluated, aiming its application in the treatment of osseous diseases. The precipitation method was used for the synthesis of HAp, EuCl3 was used for the incorporation of Eu3+ as imaging agents, silver nanoparticles (AgNPs) with antimicrobial function were used, and a model of drug, 5-fluorouracil (5FU) was used. The developed material is characterized by several techniques, where crystalline peaks attributed to HAp were identified in the X-ray diffractogram, whereas the luminescence spectrum of the material presented emissions attributed to the Eu3+ ion. The identification and the uniform distribution of AgNPs, 5FU, and Eu3+ were confirmed by mapping the sample using energy-dispersive spectroscopy. The measurements indicated that 82% (±2.8) of 5FU was incorporated into the HAp matrix, and a gradual and increasing release of it as a function of time was observed. Assays carried out for different bacteria confirmed the antimicrobial action of the samples and the efficiency of the drug inserted into the matrix. An in vitro assay showed the bioactivity of the material and its potential to bind to living osseous tissue.

La3+-doped BaSnO3 microtubes (La3+–BaSnO3) have been synthesized by electrospinning method, and the influence of La3+ content on the sensing properties of BaSnO3 for detection of formaldehyde vapor has been investigated. The as-prepared materials have been characterized using XRD, SEM, DSC, XPS, and UV-Vis. The La3+–BaSnO3 sample doped with 4 wt% La exhibited a response as high as 220 to formaldehyde vapor (1000 ppm concentration) along with a very low detection limit of 0.1 ppm at 270 °C, whereas at 140 °C, it exhibited a response of 80 and detection limit of 1 ppm. In addition, the sensor showed excellent selectivity of 57 to formaldehyde at 140 °C when compared with other vapors. Further, the sensor also showed good repeatability and stability over a long period of time suggesting its strong potential as a commercial formaldehyde sensor.

Understanding and resolving discrepancies between atom probe tomography (APT) and secondary ion mass spectrometry (SIMS) measurements of B dopants in Si-based materials has long been a problem for those in the semiconductor community who wish to measure B within the source/drain SiGe of a device. APT data collection of Si-based materials is typically optimized for Si, which is logical, but perhaps not ideal for field evaporation of B. Increasing the evaporation field well beyond the typically used 28Si2+:28Si+ ratio of approximately 10:1 up to a ratio of ~200:1 is demonstrated to improve B detection while retaining well-matched Si and Ge concentrations with respect to those measured by SIMS. A range of evaporation conditions are examined from a very low field with high laser energy to an extremely high field with extremely low laser energy demonstrating problems at both far ends of the spectrum and a sweet spot when the operating conditions used produce a 28Si2+:28Si+ ratio of approximately 200:1 (in terms of total counts of each ionization state), which is more than an order of magnitude higher than normally used conditions and results in nicely matched B, Si, and Ge APT measurements with those of SIMS.

The actual incorporation of dopant species into the ZnS Quantum Dots (QDs) host lattice will induce structural defects evidenced by a red shift in the corresponding exciton. The doping should create new intermediate energetic levels between the valence and conduction bands of the ZnS and affect the electron-hole recombination. These trap states would favour the energy transfer processes involved with the generation of cytotoxic radicals, so-called Reactive Oxygen Species, opening the possibility to apply these nanomaterials in cancer research. Any synthesis approach should consider the direct formation of the QDs in biocompatible medium. Accordingly, the present work addresses the microwave-assisted aqueous synthesis of pure and doped ZnS QDs. As-synthesized quantum dots were fully characterized on a structural, morphological and optical viewpoint. UV-Vis analyzes evidenced the excitonic peaks at approximately 310 nm, 314 nm and 315 nm for ZnS, Cu-ZnS and Mn-ZnS, respectively, Cu/Zn and Mn/Zn molar ratio was 0.05%. This indicates the actual incorporation of the dopant species into the host lattice. In addition, the Photoluminescence spectrum of non-doped ZnS nanoparticles showed a high emission peak that was red shifted when Mn2+ or Cu2+ were added during the synthesis process. The main emission peak of non-doped ZnS, Cu-doped ZnS and Mn-doped ZnS were observed at 438 nm, 487 nm and 521 nm, respectively. Forthcoming work will address the capacity of pure and Cu-, Mn-ZnS quantum dots to generate cytotoxic Reactive Oxygen Species for cancer treatment applications.

Polymeric conjugated materials are convenient for developing future soft-material-based semiconductors, conductors, electronic and optoelectronic devices due to their inherent features. Similar to their inorganic counterparts, the addition of certain minority molecules, or dopants, to polymeric conjugated materials can significantly alter the electronic and optoelectronic properties of the host conjugated polymers or composites. This allows for tunability of a variety of electronic and optoelectronic applications. One way to improve device performance is through the process of thermal annealing. Annealing allows for a polymer matrix to self-assemble into a lower energy state, which leads to an increase in crystallinity and higher charge mobility. Previous research does not explicitly define how dopants can affect this process. This study involves an evaluation of the effects of annealing with doped P3HT films to demonstrate changes in optoelectronic and electronic properties.

Chemical doping of organic semiconductors is a common technique used to increase the performance numerous organic electronic and optoelectronic devices. Tetrafluoro-tetracyanoquinodimethane (F4-TCNQ) is one of the most widely known p-dopants having the properties necessary to act as a strong electron acceptor. Despite its strong electron accepting abilities, F4-TCNQ is extremely expensive, making it less than ideal for large-area applications. Here, we introduce a small molecule called Tetracyanoindane (TCI) as a potential p-dopant. Widely known for its role in the field of non-linear optics, its high polarizability arises from the addition of four cyano-groups, which are electron withdrawing groups. The four cyano-groups are also seen in the F4-TCNQ molecule and contributes to the withdrawing strength alongside the four fluorine atoms present. We hypothesize that TCI could have similar accepting strength to F4-TCNQ and could potentially replace it as a cheaper alternative. In this study, Cyclic Voltammetry (CV), UV-Visible-Near Infrared Spectroscopy (UV/Vis/NIR), Photoluminescence (PL), Current-Voltage (IV) measurements analysis was conducted to compare the accepting strength of TCI and F4-TCNQ. Then, the two molecules were added to Poly-3-hexy-thiophene (P3HT) to observe how readily they dope the organic semiconductor.

Molecular dynamics simulations were utilized to determine the oxygen anion diffusivity in pure ceria (CeO2) and doped ceria MxCe1-xO2-0.5x (M=Gd, Sm and Pr) with varying level of dopant concentration from 5-30% (x = 0.05-0.3). Doping with Gd showed an improvement in oxygen anion diffusivity value by two order of magnitude (D = 4.67x10-8 cm2/s at 1173 K) as compared to the undoped ceria (D = 1.33x10-10 cm2/s at 1173 K). 10% of doping level was estimated as the optimum concentration of all the dopants at which all of the doped ceria materials showed maximum diffusivity of oxygen anion. Among the three dopants studied, Pr was observed to show maximum diffusivity of oxygen anion in the temperature range of 773-1173 K of simulations.

The effects of La-substitution into SrTiO3 (STO) perovskite oxides on their phase structure, formation enthalpy and electrical conductivity have been investigated. La substitution in STO has been reported to show a significant enhancement in electronic conductivity in a wide-band-gap layered perovskite compound STO. Mixture of Lanthanum and Titanium oxide may lead to various phases including La2/3TiO3, La2Ti2O7 and La2TiO5. In this work, more than 50 structural models have been constructed by considering ionic state substituents, distance between substituents and their concentrations. We investigated the formation enthalpy, elastic properties and band gap by density functional theory (DFT) calculations. We have also investigated the effect of reducing environment on La2/3TiO3. The computed bulk modulus (∼2.4 % deviation) and band gap (∼12% deviation) of STO are in good agreement with the literature. Our results indicate that La substitution into STO could significantly reduce the band gap. Reduction in band gap is maximum when the substituents is present at low concentrations. Internal position of La substituents in STO affects the band gap marginally while energy remains almost same. Formation enthalpy of La2/3TiO3 from LaTiO3 is around 2 eV. La2/3TiO3 acts as band insulator (band gap = 2.8 eV). In reducing environment, the band gap of La2/3TiO3 significantly reduces. Sr substitution in La2/3TiO3 lower the band gap and formation enthalpy. La2Ti2O7 and La2TiO5 have higher band gap and lower bulk modulus than STO. Sr substitution is not feasible in La2Ti2O7 and La2TiO5.

Polydopamine (PDA) is a biopolymer, which can form uniform thin films on almost all solid substrates as well as at the liquid/air interface. Carbonized polydopamine possesses graphite-like structure and exhibits high electrical conductivity, which makes it a potential carbon-based thin film conductor. However, studies on mechanical behavior of PDA and its derived materials are very limited. In this study, PDA samples were synthesized through self-assembly of dopamine in aqueous solution. Elastic modulus of thin films was measured using the nanoindentation technique. It is shown that the Young’s modulus of PDA thin film increased with increasing heat treatment temperature (up to 600°C). Doping with Cu ions also increased the Young’s modulus of PDA. Furthermore, all PDA thin films, with and without Cu, exhibited creep behavior.

Nb-doped TiO2 thin-films were prepared on fluorine-doped tin oxide (FTO) coated glass directly with niobium ethoxide and TiCl4 in water under the acidic conditions with several concentrations of HCl at 70-90 °C for 45 minutes or 1 hour followed by rinsing with water and annealing at 100 °C for 1 hour. Thin films of 0-1% Nb-doped TiO2 with rutile phase on FTO were obtained, which were confirmed through X-ray diffraction analyses and measurements of energy dispersive X-ray spectroscopy (EDS). Scanning electron microscopy observations equipped with EDS revealed that higher growth temperature over 90 °C is required for doping of Nb. While higher concentration of HCl resulted in much amount of Nb-doping. Band gap of rutile TiO2 gradually reduced from 3.3 eV to 3.23 eV through Nb-doping from 0% to 1%, which were estimated from uv-vis absorption spectroscopic analyses. Hall effect measurements by taking van der Pauw method confirmed that 2.26 times increase of the carrier density and 1.78 times enhancement of the conductivity have been achieved in the case of 1% Nb-doping.

Polypyrrole (PPy) thin films were synthetized by plasma and simultaneously doped with Iodine to enhance electromagnetic absorption and charge transfer capability in a resistive coupling cylindrical reactor. Pyrrole monomer and Iodine were the principal reagents used and the chemical reactions were created by high frequency plasma. Micrographs show an irregular surface formed by semi-spherical protrusions with tiny particles in the PPy/I samples and a rather smooth surface with wrinkles and less participation of tiny particles to PPy ones. Infrared spectroscopy analysis reveals important absorption peaks at 3253, 2932, 1668 and 635 cm-1 corresponding to the chemical bonds N-H and C-H, C-H aliphatic, C=C and C-I, respectively, belonging to the chemical structure of Pyrrole. Electrical conductivity of PPy increased from 10-10 to 10-8 S/cm due to Iodine doping. Electromagnetic absorption showed a higher response between 340 and 800 nm in the visible region. Activation energy was calculated in the range from -0.09 to 0.49 eV.

Li[Lix/3Mn2x/3M1−x]O2 (M = Ni, Mn, Co) (HE-NMC) materials, which can be expressed as a combination of trigonal LiTMO2 (TM = transition metal) and monoclinic Li2MnO3 phases, are of great interest as high capacity cathodes for lithium-ion batteries. However, structural stability prevents their commercial adoption. To address this, Si doping was applied, resulting in improved stability. Raman and differential capacity analyses suggest that silicon doping improves the structural stability during electrochemical cycling. Furthermore, the doped material exhibits a 10% higher capacity relative to the control. The superior capacity likely results from the increased lattice parameters as determined by X-ray diffraction (XRD) and the lower resistance during the first cycle found by impedance and direct current resistance (DCR) measurements. Density functional theory (DFT) predictions suggest that the observed lattice expansion is an indication of increased oxygen vacancy concentration and may be due to the Si doping.

Application of atom probe tomography (APT) and 1.5D secondary ion mass spectrometry (SIMS) as complimentary techniques to study fin sidewall doping by plasma implantation (PLAD) is the focus of this paper. Unlike planar transistors, characterization of 3D devices both by SIMS and APT requires sample preparation via trench backfill with α-Si, or other material, via chemical vapor deposition or atomic layer deposition process due to high aspect ratio of test structures. Certain artifacts with adverse impacts on quantitative results encountered in this study are discussed.

Piezoelectric ceramics generate strain through the intrinsic piezoelectric effect, the motion of ferroelectric domain walls, or through field-induced phase transitions. The enhanced piezoelectric properties observed in morphotropic solid solutions arise from several distinct, but interrelated, mechanisms associated with the near degeneration of the energy surface from cubic to spherical symmetry. The phenomenological theory of ferroelectricity is used to explain the thermodynamic origins of strain generation mechanisms in these solid solutions. The displacement of ferroelectric domain walls is an extrinsic contribution to the piezoelectric response that can be controlled by modifying the host material with small concentrations of dopants. The concept of “hardening” is introduced; hardening can be useful in applications where piezoelectric energy conversion and low energy loss are more important than large strain. The operative mechanisms of strain generation and energy conversion in technologically important lead-based and lead-free piezoelectric materials are summarized.