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Ge Complementary Tunneling Field-Effect Transistors Featuring Dopant Segregated NiGe Source/Drain
摘要： Ge complementary tunneling field-effect transistors (TFETs) are fabricated with the NiGe metal source/drain (S/D) structure. The dopant segregation method is employed to form the NiGe/Ge tunneling junctions of sufficiently high Schottky barrier heights. As a result, the Ge p- and n-TFETs exhibit decent electrical properties of large ON-state current and steep sub-threshold slope (?? factor). Especially, ??d of 0.2 ??A/??m is revealed at ??g ? ??th = ??d = ±0.5 V for Ge pTFETs, with the ?? factor of 28 mV/dec at 7 K.
关键词： ON-state current,NiGe metal source/drain,Ge complementary tunneling field-effect transistors,sub-threshold slope,Schottky barrier heights,dopant segregation
更新于2025-09-10 09:29:36
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Effect of precursor dopant valence state on the photocatalytic performance of Mo3+- or Mo5+-Doped TiO2 thin films
摘要： Mo3+- or Mo5+-doped TiO2 sol-gel thin films (≤0.100 mol%) were spin coated on fused silica glass substrates and annealed at 450°C for 2 h. The effect of the valence of the dopant precursor is significant to the nanostructural development and resultant properties. Mo3+ or Mo5+ doping yields converse trends with doping level, thus reflecting the competing influences of lattice distortion and destabilization (dominating Mo3+ doping) and nucleation and recrystallization (dominating Mo5+ doping). Mo doping results in oxidation of Mo3+ and reduction of Mo5+, both of which alter to Mo(5-x)+, as well as oxidation of Ti3+ to Ti(4+x)+; all of these result in (cid:1)(cid:2) annihilation. Although the absorption edges were largely indistinguishable Mo3+ doping causes a red shift and Mo5+ doping causes a blue shift. These data suggest that the performances are controlled by the synergistic effects of crystallinity, surface area, and band gap, with the latter’s exhibiting the dominant effect. This suggests that the defect structure governs the photocatalytic performance but also that the defect chemistry at these low annealing temperatures is indicative of nonequilibrium conditions, thereby explaining the significance of the dopant valence.
关键词： Photocatalysis,Dopant Valence,Anatase,Thin Film,Titania
更新于2025-09-10 09:29:36
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Stone-Wales like defects formation, stability and reactivity in black phosphorene
摘要： During the synthesis of ultra-thin materials with a hexagonal lattice structure, Stone-Wales (SW) type of defects are quite likely to be formed that can result in dramatic changes in their electronic and mechanical properties. Here we investigated the formation and reactivity of SW-like defects in Phosphorene. Our calculations show that the energy barrier for the formation of SW-like defects in phosphorene is significantly lower than in graphene. Moreover, the nature of phosphorene provides a large energy barrier for the healing of the SWL defect, therefore defective phosphorene is stable. SWL-defect phosphorene are semiconductors with bandgap wider than pristine phosphorene that depends on the density of defects. Furthermore, nitrogen substitution in SWL defected phosphorene shows that defect lattice sites are the least preferable substitution locations for the N atoms. Easy formation of SWL defects in phosphorene provides a guideline for bandgap engineering in phosphorene based materials through such defects.
关键词： Dopant,Electronic Structure,Phosphorene,Nitrogen,Stone-Wales-like defects
更新于2025-09-10 09:29:36
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Dielectric, Ferroelectric, and Magnetic Properties of Sm-Doped BiFeO3 Ceramics Prepared by a Modified Solid-State-Reaction Method
摘要： Sm-doped BiFeO3 (BFO) material was prepared using a modified solid-state-reaction method, which used fast heating and cooling during the sintering process. The Sm doping level varied between 1 mol % to 8 mol %. Processing parameters, such as sintering temperature and annealing temperature, were optimized to obtain high-quality samples. Based on their dielectric properties, the optimum sintering and annealing temperatures were found to be 300 ?C and 825 ?C, respectively. Leakage-free square-shaped ferroelectric hysteresis loops were observed in all samples. The remnant polarization was maximized in the 5 mol %-doped sample (~35 μC/cm2). Furthermore, remnant magnetization was increased after the Sm doping and the 8 mol%-doped sample possessed the largest remnant magnetization of 0.007 emu/g. Our results demonstrated how the modified solid-state-reaction method proved to be an effective method for preparing high-quality BiFeO3 ceramics, as well as how the Sm dopant can efficiently improve ferroelectric and magnetic properties.
关键词： dielectric,Sm dopant,magnetic,ferroelectric,BFO
更新于2025-09-10 09:29:36
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Effect of Cadmium Dopant on Structure and Optical Properties of ZnO Thin Films Prepared by Spray Pyrolysis Technique
摘要： Effect of Cadmium Dopant on Structure and Optical Properties of ZnO Thin Films Prepared by Spray Pyrolysis Technique
关键词： Spray Pyrolysis Technique,Optical Properties,ZnO Thin Films,Cadmium Dopant
更新于2025-09-10 09:29:36
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Mg doped CdO thin films grown on glass substrate by spray pyrolysis method
摘要： The undoped and various magnesium (Mg) doped cadmium oxide (CdO) thin films were synthesized by spray pyrolysis technique. Structural, optical and morphological examinations of the samples were carried out via various instruments. X-ray diffraction (XRD) and Raman spectroscopic measurements of the samples were performed to obtain structural properties. Ultraviolet (UV)-visible and photoluminescence (PL) spectroscopy measurements as well as scanning electron microscopy (SEM) were employed to characterize optical and morphological properties of the undoped and Mg doped CdO thin film. XRD measurements revealed that both the undoped and Mg doped CdO thin films demonstrated a cubic structure and had preferential orientations along the (200) plane. In the Raman spectrum, it was observed that the peak (266 cm?1) of the first peak belonging to the CdO thin film disappeared and the second main peak (908 cm?1) shifted to higher energies with the Mg dopant. As a result of the absorbance measurements, the band range of the samples showed a shift of the band gap from 2.15 eV to 2.43 eV with the Mg dopant, and the Burstein-Moss effect indicated a shift to gray scale and decreased from 67% to 59% in transmittance measurements. The PL results exhibited that both the undoped and Mg doped CdO thin films had a UV emission of 394 nm (3.15 eV), blue emission of 434 nm (2.86 eV), blue-yellow emission of 540 nm (2.30 eV), 735 nm (1.69 eV) and emission of 782 nm (1.59 eV). The SEM measurements indicated that the CdO thin films changed from pyramidal structures to random shape with Mg dopant.
关键词： optical properties,Mg dopant,CdO thin film
更新于2025-09-09 09:28:46
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Influence of Ba/Ti ratio on PTCR effect of Bam(Ti1?xNbx)O <sub/>3</sub> ceramics prepared by the reduction sintering-reoxidation method
摘要： In this work, we investigate the influences of Ba/Ti ratio and sintering conditions on the characteristics of positive temperature coefficient of resistance (PTCR) and electrical properties of Bam(Ti1?xNbx)O3 (BTN) ceramics. The ceramics were fired at 1190?C for 0.5–6.0 h in a reducing atmosphere and then reoxidized at 600–650?C for 0–8 h. The Ba/Ti ratio (m) affected the electrical properties and PTCR effect of the BTN specimens. The room-temperature (RT) resistance of the BTN samples initially decreased (0.994 < m < 1.006) and then increased (1.006 < m < 1.018) as the Ba/Ti ratio increased. Moreover, BTN ceramics exhibit a pronounced PTCR effect, with a resistance jump greater by 3.0 orders of magnitude and a low 0.1 ? RT resistance at a low reoxidation temperature of 600?C after sintering under a reducing atmosphere. Furthermore, the average sample grain size increased along with the Ba/Ti ratio. In addition, the influence of the sintering time and the reoxidation time on the electrical properties and the PTCR effect were also investigated.
关键词： PTC effect,Nb2O5-dopant,Ba/Ti ratio,BaTiO3
更新于2025-09-09 09:28:46
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Branched Side Chains Govern Counterion Position and Doping Mechanism in Conjugated Polythiophenes
摘要： Predicting the interactions between a semi-conducting polymer and dopant is not straightforward due to the intrinsic structural and energetic disorder in polymeric systems. Although the driving force for e?cient charge transfer depends on a favorable o?set between the electron donor and acceptor, we demonstrate that the e?cacy of doping also relies on structural constraints of incorporating a dopant molecule into the semiconducting polymer ?lm. Here, we report the evolution in spectroscopic and electrical properties of a model conjugated polymer upon exposure to two dopant types: one that directly oxidizes the polymeric backbone and one that protonates the polymer backbone. Through vapor phase in?ltration, the common charge transfer dopant, F4-TCNQ, forms a charge transfer complex (CTC) with the polymer poly(3-(2′-ethyl)hexylthiophene) (P3EHT), a conjugated polymer with the same backbone as the well-characterized polymer P3HT, resulting in a maximum electrical conductivity of 3 × 10?5 S cm?1. We postulate that the branched side chains of P3EHT force F4-TCNQ to reside between the π-faces of the crystallites, resulting in partial charge transfer between the donor and the acceptor. Conversely, protonation of the polymeric backbone using the strong acid, HTFSI, increases the electrical conductivity of P3EHT to a maximum of 4 × 10?3 S cm?1, 2 orders of magnitude higher than when a charge transfer dopant is used. The ability for the backbone of P3EHT to be protonated by an acid dopant, but not oxidized directly by F4-TCNQ, suggests that steric hindrance plays a signi?cant role in the degree of charge transfer between dopant and polymer, even when the driving force for charge transfer is su?cient.
关键词： semiconducting polymer,electrical conductivity,steric hindrance,dopant,charge transfer
更新于2025-09-09 09:28:46
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Three in one: Mesogenic aromatic acid as a liquid crystal matrix, a chiral dopant in liquid crystals and a stabilizer for nanoparticles
摘要： Studies of thermodynamics of the N*-I phase transitions and optical properties of the new liquid crystal - (R)-2-[4”-(trans-4-butylcyclohexyl)-2’-chloro-p-terphenyl-4-oxy) propanoic acid are carried out. The aim of these studies is to analyse the capabilities of that liquid crystal to simultaneously serve as a matrix for inorganic semiconductor nanoparticles (NP) as well as a chiral dopant for liquid crystals and a chiral ligand stabilizing the surface of CdSe NPs. The chiral doping of a nematic liquid crystal was proven by the measurements of selective transmittance of the visible light. The embedding of NPs in a nematic liquid crystal leads to the increase in TN*I, which is explained by the shape anisotropy of the NPs. The anisotropy of the ligand shell may result from the interaction between the ligand and LC matrix inducing the change of the spherical shape of the shell toward the ellipsoidal one. TN*I of the liquid crystal matrix of (R)-2-[4”-(trans-4-butylcyclohexyl)-2’-chloro-p-terphenyl-4-oxy) propanoic acid (R-MPA) decreases with the embedding of NPs stabilized by the same ligands, which is in a good agreement with prior experimental results and theory, but there exists a considerable quantitative difference.
关键词： optical properties,liquid crystal,thermodynamics,nanoparticles,chiral dopant
更新于2025-09-09 09:28:46
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The enhancement of humidity sensing performance based on Eu-doped ZnO
摘要： In this work, a high performance impedance-type humidity sensor based on Europium-doped ZnO with abundant surface oxygen vacancy defects was synthesized by sol-gel method. Response of the Eu-doped ZnO with di?erent molar ratio were investigated by exposing them to humidity environments in wide range of 11–95% RH at room temperature. The Eu-doped ZnO (2 mol%) exhibits a three orders impedance change, along with short response/recovery time (5 s/19 s), low hysteresis and best linearity. Complex impedance spectra indicates that dopant Eu can enhance humidity sensing performance of ZnO, which is resulted from the introduction of Eu3+ ions into ZnO structure to produce more defects of surface oxygen vacancy and more active sites on the surface of ZnO. The results show that this is a feasible method to achieve high humidity sensing performance by Eu doped ZnO, which make it a promising candidate for humidity sensing materials and broaden the use of ZnO materials.
关键词： Eu dopant,Humidity sensors,Sol-gel,Zinc oxide
更新于2025-09-04 15:30:14