Doping Rate Research Articles

(Invited) Ultrawide Bandgap β-Ga2O3 Thin Films: Growths, Properties and Devices

Ultrawide bandgap (UWBG) gallium oxide (Ga2O3) represents an emerging semiconductor material with excellent chemical and thermal stability up to 1400 oC. It has a band gap of 4.5-4.9 eV, much higher than that of the GaN (3.4 eV) and 4H-SiC (3.2 eV). It exhibits high transparency in the deep ultraviolet (DUV) and visible wavelength region due to its very large bandgap. The monoclinic b-phase Ga2O3 represents the thermodynamically stable crystal among the known five phases (α, β, γ, δ, ε). The breakdown field of β-Ga2O3 is estimated to be 8 MV/cm, which is about three times larger than that of 4H-SiC and GaN. These unique properties make β-Ga2O3 a promising candidate for high power electronic device and solar blind photodetector applications. More advantageously, single crystal β-Ga2O3 substrates can be synthesized by scalable and low cost melting based growth techniques such as edge-defined film-fed growth (EFG), floating zone (FZ) and czochralski methods. For β-Ga2O3 thin film synthesis, both molecular beam epitaxy (MBE) and metalorganic vapor phase epitaxy (MOVPE) have been demonstrated to produce high quality and controllable doping films but with slow growth rates (2-10 nm/min). Halide vapor phase epitaxy (HVPE) using chloride precursors was demonstrated to grow β-Ga2O3 films with fast growth rates (>5 μm/hr). Recently, we have developed a low pressure chemical vapor deposition (LPCVD) method to grow high quality β-Ga2O3 thin films on both native Ga2O3and c-sapphire substrates with controllable doping and fast growth rates up to 10 μm/hr. In this talk, we present a study on the defects in β-Ga2O3 thin films grown via LPCVD. The β-Ga2O3 thin films were grown on native β-Ga2O3 substrates and sapphire substrates using high purity gallium and oxygen as the precursors, and argon (Ar) as the carrier gas. The growth temperature ranged between 850 ˚C and 950 ˚C. The β-Ga2O3 thin films were characterized by using field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM). FESEM images were taken with Helios 650. High resolution transmission electron microscopy (HRTEM) images and selected-area electron diffraction (SAED) were taken using a FEI Tecnai F30 at 300 kV. Bright field, dark field, combined with two-beam condition TEM were used to characterize the defects in the as-grown films. From our studies, β-Ga2O3 thin films grown on (010), (001) and (-201) β-Ga2O3 substrates have shown different growth rates as well as different properties of interfacial defects. Improved LPCVD growths to suppress defects in β-Ga2O3thin films grown on different substrates will be discussed. Room temperature Hall measurements will be performed to understand the dependence of carrier transport on defects. In summary, the fundamental defect studies are performed on β-Ga2O3 thin films grown via LPCVD on Ga2O3 and sapphire substrates. The results from this study are important knowledge for power device applications.

Polymorphic immune molecules in gametes and gametal fluids

In this work, a ternary photonic crystal having an n-doped semiconductor as a defect layer is considered. Tunable properties of the transmission spectra are investigated for TE waves. The three layers of the proposed photonic crystal are Si, Bi4Ge3O12 and SiO2 and the defect layer is n-GaAs. The transmission properties and defect mode of the structure may be controlled by using the doping rate, applied magnetic field and width of the n-GaAs layer. The defect layer width is found the most efficient factor among these three factors. The analysis is performed in the near-infrared spectral region. The proposed structure can be used to construct filters with narrowband transmission peaks.

Influence of fluorine doping on the microstructure, optical and electrical properties of SnO2 nanoparticles

Tin dioxide (SnO2) is one of the most promising functional semiconductor materials; it has stimulated considerable research interest for its wide applications such as optoelectronic devices and solar cells technology. Undoped and fluorine doped tin oxide aerogel nanoparticles have been successfully synthesized by sol–gel route and dryed under supercritical conditions of ethanol. The effect of fluorine concentration on SnO2 nanoparticles properties was systematically investigated by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, Raman spectroscopy, UV–Vis–IR spectroscopy and impedance spectroscopy. Characterization data showed that both pure SnO2 and FTO aerogels have a polycrystalline tetragonal rutile structure with a highly (110) plane preferred orientation. The grain sizes in the range of 11–25 nm were obtained depending on the elaboration conditions. Raman spectra show the fundamental peaks at 477, 632, and 782 cm−1, corresponding to the Eg, A1g, and B2g vibration modes, respectively, in good agreement with those for the rutile bulk SnO2. The optical band gap value of tin oxide decreases from 3.88 to 3.44 eV with the increase of fluorine content. Impedance spectroscopy results indicate that the electrical properties are strongly dependent on temperature and doping rate. These results show the strong correlation between the structural, morphological, optical and electrical properties of the samples depending on doping content which was well reflected on the quality of the nanoparticles.

Current Status of Doping in Japan Based on Japan Anti-Doping Disciplinary Panels of the Japan Anti-Doping Agency (JADA): A Suggestion on Anti-Doping Activities by Pharmacists in Japan.

In 2009, the Japan Anti-Doping Agency (JADA) established the "Sports Pharmacist Accreditation Program" to prevent doping in sports. Since then, anti-doping activities in Japan have been attracting attention. In this study, we investigated research about the current status of doping from 2007 to 2014 in Japan to make anti-doping activities more concrete, and we also discussed future anti-doping activities by pharmacists. In Japan, bodybuilding was the sporting event with the highest number and rate of doping from 2007 to 2014. Many of the positive doping cases were detected for class S1 (anabolic agents), S5 (diuretics and masking agents), and S6 (stimulants). Within class S1, supplements were the main cause of positive doping. Within class S5, medicines prescribed by medical doctors were the main cause of positive doping. Within class S6, non-prescription medicines (e.g., OTC) were the main cause of positive doping. When we looked at the global statistics on doping, many of the positive doping cases were detected for class S1. On comparing the Japanese statistics with the global statistics, the rate of positive doping caused by class S1 was significantly lower, but that caused by classes S5 and S6 was significantly higher in Japan than in the world. In conclusion, pharmacists in Japan should pay attention to class S1, S5, and S6 prohibited substances and to the sport events of bodybuilding. Based on this study, sports pharmacists as well as common pharmacists should suggest new anti-doping activities to prevent doping in the future.

Study of some photic properties of thin membranes of zinc oxide, which is affected by different percentages of aluminum

يهــدف هــذا الـبحـث إلى تحضيـر أغــشــية رقيقة من أكســيد الزنــك ( Zn O ) المشـوب بـنسـب % 10 - % 20 - % 30 - % 40 مـن الألــومـنــيــوم بتــقــنــيـــة المحلول الجيلاتيني ( sol – gel ) ، ودراســـــة بعـــض الخـصائـــص الضـوئــــيــة لهـا مثل الإمتصاصية ومعامل الإمتصاص ومعامل الخمود والنفاذية مـن خــلال تسجـيـــل طـــيـف الإمــتــصـــاص مـن جـهــــاز مــطــيــافــيــة الأشـــــعــــة فــوق البـنـفــســجـــيـة والمـرـئـيـــة ومعالجــتــه بـبــرنــامج Orginal 8.6 . وقــد أجــريــت الــدراســــــة ضمــن مـــدى الأطـــوال المــوجــــيـــة nm( 900 – 300 ) وقــد تم دراسة كلا من الإمتصاصية ومعامل الإمتصاص ومعامل الخمود وطيف النفاذية كدالة للطول الموجي و وجـــد أن الإمتـصاصـيـة تـقــل بـــزيــادة نــســـب التــشــوـيـب ضمن مـدى الــطــول المــوجــيnm ( 550- 400 ) حـــيــث بلغــت قــــيــم الإمـتـــصـاصـيـــــة a u 0.338 للعينة المشوبة بنسبة % 10 من الألومنيوم ثم تناقصت قيم الإمتصاصية و أخذت أقل قيمة لها عند نسبة تشويب بالألومنيوم % 40 وبلغت au 0.019 ، ووجد أن معامل الإمتــصاص يــقــل أـيـــضا ـبــزيــــادة نــســـب التـــشـــــويــب ضـمن نــفــس مــدى الطــول الـمــوجـــي حـــيـــث أخـــذت أعلى قيمة لها عـند نسبة تشويب بالألــومنــيــــوم % 10 وكانت cm-1 105 × 7.7 ثم تناقصت مع زيادة نسب التشويب و أخذت أقل قيمة لها عند نسبة تشويب بالألومنيوم % 40 وكانت cm-1 104 × 3 و أن معامل الخمود يقل بزيادة نسب التشويب فأخذت أعلى قيمة وتعادل 0,285 للعينة ذات نسبة تشويب بالألومنيوم % 10 ثم تناقصت مع زيادة نسب الألومنيوم ووصلت إلى 0.017 لنـسـب الـــتـــشــــــويــب بالألـــومنــيــوم % 40 ، وتبين أن النفاذية للأغشية الرقيقة لأكسيد الخارصين تزيد بزيادة نسب تشويبها بالألومنيوم أخذت أقل قيم لها عند نسبة تشويب % 10 وبلغت 1,9987 ثم ازدادت قيمتها إلى أن وصلت إلى 2,0023 عند العينة ذات نسبة تشويب % 40 .

Fabrication of Porous Current Collectors for Li Ion Capacitor with Pico-Second Pulse Laser and Acceleration of Li+ Ion Pre-Doping Reaction to Laminated Graphite/Porous Current Collector Anodes

The fabrication process of porous copper (Cu) current collectors having the pore diameter (3-50 mm) and the rate of opening area (1-4 %) was developed with a system constructed with a pico-second pulse laser and a polygon mirror. The fabricated porous Cu current collectors (Fig. 1) were used to evaluate the porous design on the Cu current collector for exhibiting higher Li+ doping reaction rate with cells in which graphite electrodes were laminated with separators and the laminated graphite anode opposites to Li metal through a separator (Fig. 2). It was found in this study that the conditions of hole diameter (5 mm) and the rate of opening area (1%) is the best one to realize high Li+ doping rate and that the rate determining step of the pre-doping reaction is the diffusion of Li+ion in the pore of the Cu porous current collectors. Fig. 1 Surface SEM images of prepared porous Cu current collectors. Magnified SEM image of a pore: (A) a view from the plane of incidence of a laser, (B) a view from the plane of emission of a laser. Opening rate of pore on the current collectors: (C) 1 and (D) 2.5 %. The pore size is a constant of 20 mm in all SEM images. Fig. 2 Schematic description of a cell for pre-doping reaction with graphite layer/porous current collector anodes and a Li metal. Figure 1

Two‐particle self‐consistent analysis for the electron‐hole asymmetry of superconductivity in cuprate superconductors

In the hole‐doped type cuprate superconductors, it is well‐known that the superconducting transition temperature Tc exhibits a dome‐like structure against doping. On the other hand, recent experiments unveil that Tc in the electron‐doped compounds shows a monotonic increase with decreasing the doping, at least down to a very small doping rate. Our recent study for the three‐band d–p model has unveiled that this asymmetric behavior can be explained as a combined effect of the intrinsic electron‐hole asymmetry in systems comprising Cu3 d and O2 p orbitals and the band‐filling‐dependent vertex correction . In the present study, we study another compound Tl2 Ba2 CuO6 to show that this explanation can be applied to other cuprate superconductors with the small orbital mixture. By varying the d–p offset, we also study how the strength of the d–p hybridization controls the spin fluctuation and hence the pairing interaction.

積層型グラファイト/穴あき集電箔負極における集電箔上の開口条件および反応温度とLi<sup>+</sup>イオンプレドープ速度との関係

The fabrication process of porous copper (Cu) current collectors having the pore diameter (3–50 µm) and the rate of opening area (1–4%) was developed with a system constructed with a pico-second pulse laser and a polygon mirror. The fabricated porous Cu current collectors were used to evaluate the porous design on the Cu current collector for exhibiting higher Li+ doping reaction rate with cells in which graphite electrodes were laminated with separators and the laminated graphite anode opposites to Li metal through a separator. It was found in this study that the conditions of hole diameter (5 µm) and the rate of opening area (1%) is the best one to realize high Li+ doping rate and that the rate determining step of the pre-doping reaction is the diffusion of Li+ ion in the pore of the Cu porous current collectors.

Effect of Vanadium Doping on Microstructure and Dielectric Behavior of CaCu<sub>3</sub>Ti<sub>4</sub>O<sub>12</sub> Ceramics

In this work, effect of vanadium doping of CaCu₃Ti₄O₁₂ (CCTO) on microstructure and complex dielectric constant over wide frequency (100 Hz-1 MHz) and temperature (0°C – 160°C) ranges has been studied. The vanadium doping of CCTO system results in an increase of grain size, the grains being surrounded by melted-like grain boundaries. Real parts of dielectric constant of all samples are similar at low frequency (<1 kHz). In doped samples, above 1 kHz, a relaxation appears which is evidenced by a drop of real part of permittivity and a peak of its imaginary part. This relaxation phenomenon is very significant at relatively low doping rates and then decreases again as vanadium content increases. AC conductivity behavior of vanadium-doped CCTO can be divided in three regions depending on conduction processes. The calculated activation energies were close to 0.46 eV.

Staggered Flux State in Two-Dimensional Hubbard Models

The stability and other properties of a staggered flux (SF) state or a correlated d-density wave state are studied for the Hubbard (t-t'-U) model on extended square lattices, as a low-lying state that competes with the d(x2-y2)-wave superconductivity (d-SC) and possibly causes the pseudogap phenomena in underdoped high-Tc cuprates and organic kappa-BEDT-TTF salts. In calculations, a variational Monte Carlo method is used. In the trial wave function, a configuration-dependent phase factor, which is vital to treat a current-carrying state for a large U/t, is introduced in addition to ordinary correlation factors. Varying U/t, t'/t, and the doping rate (delta) systematically, we show that the SF state becomes more stable than the normal state (projected Fermi sea) for a strongly correlated (U/t\gtrsim 5) and underdoped (delta\lesssim 0.16) area. The decrease in energy is sizable, particularly in the area where Mott physics prevails and the circular current (order parameter) is strongly suppressed. These features are consistent with those for the t-J model. The effect of the frustration t'/t plays a crucial role in preserving charge homogeneity and appropriately describing the behavior of hole- and electron-doped cuprates and kappa-BEDT-TTF salts. We argue that the SF state does not coexist with d-SC and is not a `normal state' from which d-SC arises. We also show that a spin current (flux or nematic) state is never stabilized in the same regime.

MoS$_2$ Broadband Coherent Perfect Absorber for Terahertz Waves

We present a comprehensive analysis of terahertz waves propagation through a bulk MoS $_2$ crystal slab. It is shown that broadband coherent perfect absorption can be achieved and the coherent absorptivity can be adjusted from 1.57% to 99.97% by means of phase modulation. Moreover, the relative bandwidth for over 90% coherent absorptivity can be as wide as 179%. By increasing the doping rate in MoS $_2$ crystal, the coherent absorptivity spectrum exhibits a clear blueshift whilst the peak coherent absorptivity remains over 99.9%. Full-wave numerical simulations are further carried out to confirm the validity of our theoretical analysis.

Mesh-structured N-doped graphene@Sb2Se3 hybrids as an anode for large capacity sodium-ion batteries

A mesh-structured N-doped graphene@Sb2Se3 (NGS) hybrid was one-pot prepared to realize N-doping, nanostructuring and hybridization for a sodium-ion battery anode to deliver much larger reversible specific capacity, faster interfacial electron transfer rate, better ionic and electronic transport, higher rate performance and longer cycle life stability in comparison to the plain Sb2Se3 one. The better performance is ascribed to the unique intertwined porous mash-like structure associated with a strong synergistic effect of N-doped graphene for dramatic improvement of electronic and ionic conductivity by the unique porous structure, the specific capacity of graphene from N doping and fast interfacial electron transfer rate by N-doping induced surface effect and the structure-shortening insertion/desertion pathway of Na+. The detail electrochemical process on the NGS electrode is proposed and analyzed in terms of the experimental results.

SECM investigation of electrochemically synthesized polypyrrole from aqueous medium

The electrochemical behavior of polypyrrole (PPy)-coated carbon steel (CS) was investigated in aqueous NaCl solution by scanning electrochemical microscopy. Oxygen concentration and pH were monitored by placing Pt and Sb microelectrodes, respectively, over the CS sample surfaces while soaking them in corrosion media. The PPy layer provided anodic protection, as well as a physical barrier, against the corrosive effect. The ratio of these properties was dependent on the thickness of the coating. Electrosynthesis of PPy/CS was achieved in an aqueous solution of sodium tartrate and pyrrole using cyclic voltammetric and galvanostatic techniques. The coatings were characterized by X-ray photoelectron spectroscopy and scanning electron microscopy. The doping rate calculated from XPS spectra was estimated at 15 %. The corrosion protective extent of the coating was tested in 3 % NaCl solution using three different techniques: linear polarization, open circuit potential, and electrochemical impedance spectroscopy. PPy offered significant protection against corrosion, with the coating resistance decreasing as immersion time increased.

Tritium-doping enhancement of polystyrene by ultraviolet laser and hydrogen plasma irradiation for laser fusion experiments

We investigate the tritium-doping enhancement of polystyrene by ultraviolet (UV) laser and hydrogen plasma irradiation. Tritium-doped polystyrene films are fabricated by the Wilzbach method with UV laser and hydrogen plasma. The 266-nm laser-irradiated, 355-nm laser-irradiated, and hydrogen plasma-irradiated polystyrene films exhibit higher PSL intensities and specific radioactivities than the non-irradiated sample. Tritium doping by UV laser irradiation can be largely affected by the laser wavelength because of polystyrene’s absorption. In addition, UV laser irradiation is more localized and concentrated at the spot of laser irradiation, while hydrogen plasma irradiation results to a more uniform doping concentration even at low partial pressure and short irradiation time. Both UV laser and plasma irradiations can nevertheless be utilized to fabricate tritium-doped polystyrene targets for future laser fusion experiments. With a high doping rate and efficiency, a 1% tritium-doped polystyrene shell target having 7.6×1011Bqg−1 specific radioactivity can be obtained at a short period of time thereby decreasing tritium consumption and safety management costs.

Laser output power losses in ceramic Nd:YAG lasers due to thermal effects

Laser output power losses in a ceramic Nd:YAG laser with a doping rate of 2at.% Nd3+ due to thermal effects were analyzed. The ceramic Nd:YAG laser output power losses due to thermal birefringence effects and thermal lens effects were measured via changes in the output power of the ceramic Nd:YAG laser. At a pump power of 12W, the total laser output power loss, the loss due to the thermal lens, and the loss due to thermal birefringence were found to be 68.7%, 48.1%, and 20.6%, respectively.

Control of the LiFePO4 electrochemical properties using low-cost iron precursor in a melt process

LiFePO4 was prepared from low-cost iron ore concentrate (containing 4.48 wt.% SiO2 and MgO, CaO and Al2O3 below 0.5 wt.% as contaminant) using a melt synthesis. X-ray diffraction (XRD) refinement associated with Mossbauer spectroscopy and scanning electron microscopy-energy dispersive spectroscopy (SEM-EDX) analyses are used to track the location of Si in the material. It is shown that the iron content in the melt can be used as a means to control the doping rate of elements from iron ore concentrate (IOC) precursor according to the formula (Li1 − zAz)(Fe1 − yMy)(P1 − xSix)O4. Electrochemical behavior of the material is affected by the doping of LiFePO4. While capacity is decreased in doped material, the cycling stability is much improved. When dopants are out of LiFePO4 structure, capacity retention dramatically drops as well as capacity due to the gravimetric impact of impurity phases. A trade-off between high capacity and best cycling performance is necessary. For instance, slight lack of iron in the melt (6 % deficiency) leads to a capacity only 2 % lower than that of pure Fe2O3-based material for the same stoichiometry and fairly good capacity retention.

Tuning the Mn and Fe Valence States into New Ca0.7Mn2–xFexO4 (0 &lt; x ≤ 0.60) Solid Solution during Reversible Redox Processes

New Mn4+-rich Ca0.7Mn2–xFexO4 complex oxides (0 < x ≤ 0.6) with Mn4+ amount varying from 33% to 43% have been prepared by aqueous self-combustion routes and characterized by powder X-ray Diffraction (XRD) and Mössbauer spectroscopy. These oxides crystallize with a monoclinic symmetry (CaMn3O6-type, space group P21/a) for low Fe content and with an orthorhombic symmetry (CaFe2O4-type, space group Pnma) for x > 0.14, thus stabilizing the highest Ca defects content (30%) for this series. A regular decrease of the Jahn–Teller Mn3+ site distortion is observed versus Fe content. For low iron content (x < 0.33), Fe3+ ions are preferentially but not exclusively located at the Mn4+-rich site which exhibits lower octahedral distortion, whereas for higher iron doping rates (x ≥ 0.33), Fe3+ ions are almost equally distributed in the two more or less distorted transition metal sites. The same distribution of Fe3+ in both of these atomic positions contributes to the stabilization within these phases of a high content of Mn4+ even at higher temperatures (T > 1000 °C), whereas the unsubstituted Ca0.66Mn2O4 phase is only stable up to 850 °C. Furthermore, these phases can be reduced at T = 550 °C under Ar/5% H2 into a Mn2+ and Fe2+/Fe3+ phase based on the rock salt structure and then reoxidized at T = 700 °C under air to get pure phases with the same orthorhombic unit cell and a Fe3+ distribution in the two atomic positions similar to the initial phase. Despite the additional stabilization of metal iron Fe0 during the reduction at T > 550 °C, a pure Mn4+/Mn3+/Fe3+-based oxide with CaFe2O4-type structure has been recovered after oxidation at T > 700 °C under air. Mössbauer spectroscopy of the reduced phase has revealed the presence of Fe2+ ions at two distinct octahedral sites corresponding to Fe3+ within the oxidized phase. The reversibility of this redox system could be explained by the occurrence of two rutile double chains in the CaFe2O4-type network, which is closely related to the rock salt structure with Ca2+ ions in the vicinity of Mn and Fe atoms. During the steps of oxygen release and storage, this network, derived from the rock salt framework, seems to preserve the Fe and Mn organization at the local scale.

Artificial multiferroic structures based on barium-strontium titanate

Artificial extrinsic and intrinsic multiferroic structures were developed in the form of yttrium-iron garnet/barium-strontium titanate bi-layers and manganese-doped barium-strontium titanate films with a relatively high doping rate in the range of 10–20 mol%. For the experimental investigations, the planar capacitors were formed on the surfaces of the structures and the capacitance–voltage characteristics were measured. Structural characterization of the samples under study was based on X-ray diffraction analysis and film–substrate interfaces were investigated by X-ray photoelectron spectroscopy. The relative dielectric permittivity, dielectric loss tangent, and electric field tunability of the samples were measured in a temperature range from 77 to 300 К. The additional 6 and 3 % tuning of the dielectric permittivity by external magnetic field of 2000 Oe was demonstrated for the extrinsic and intrinsic structures, respectively.

Characterization of DMS Zn1-xAxO (A: Fe, Ni, Co and Mn, x: 0.01, 0.02, …, 0.1) grown by ECD method

Zn1-xAxO (A: Fe, Ni, Co and Mn, x: 0.01, 0.02,…, 0.1) films, grown by electrochemical deposition (ECD) on indium tin oxide (ITO) substrate, was characterized by structural, optical, electrical and magnetic techniques. Energy-Dispersive-X-Ray-Fluorescence (EDXRF) spectroscopy showed 5% dopants A. X-ray diffraction (XRD) measurements clearly showed formation of all Zn0,95A0,05O thin films with a strong c-axis (002) preferential orientation. It was calculated a hexagonal wurtzite structure with XRD results. Absorption measurements of the samples were taken about and an important variation in these measurements were not detected as depend on percentage changes of dopant A. Photoluminescence (PL) measurements showed that PL intensities increase in n-type materials, decrease in p-type materials depending upon increasing doping rate of the grown films. Atomic force microscopy (AFM) pictures of films shows that the most homogeny film is Zn0,95Co0,05O and the most roughness film Zn0,95Mn0,05O. Hall measurements showed that samples doped 5% Fe and Co within ZnO are n-type and other samples doped 5% Ni and Mn within ZnO are p-type. Magnetoresistance (MR) measurements show that all films have feature diluted magnetic semiconductor (DMS) at room temperature.

Influence of Gate Material and Process on Junctionless FET Subthreshold Performance

The recent progress of dimension scaling of electronic device into nano scale has motivated the invention of alternative materials and structures. One new device that shows great potential to prolong the scaling is junctionless FET (JLFET). In contrast to conventional MOSFETs, JLFET does not require steep junction for source and drain. The device processing directly influence the performance, therefore it is crucial to understand the role of gate processing in JLFET. This paper investigates the influence of gate material and process on subthreshold performance of junctionless FET, by comparing four sets of gate properties and process techniques. The result shows that in terms of subthreshold slope, JLFET approaches near ideal value of 60 mV/decade, which is superior than the SOI FET for similar doping rate. On the other hand, the threshold value shows different tendencies between those types of device.