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1.
Electrical devices involve different types of diode in prospective electronics is of great importance. In this study, p-type Si surface was covered with thin film of TiO2 dispersion in H2O to construct p-Si/TiO2/Al Schottky barrier diode (D1) and the other one with TiO2 dispersion doped with zirconium to construct p-Si/TiO2-Zr/Al diode (D2) by drop-casting method in the same conditions. Electrical properties of as-prepared diodes and effect of zirconium as a dopant were investigated. Current–voltage (I–V) characteristics of these devices were measured at ambient conditions. Some parameters including ideality factor (n), barrier height (ΦB0), series resistance (Rs) and interface state density (Nss) were calculated from I–V behaviours of diodes. Structural comparisons were based on SEM and EDX measurements. Experimental results indicated that electrical parameters of p-Si/TiO2/Al Schottky device were influenced by the zirconium dopant in TiO2. 相似文献
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Kang-Pil Kim Sang-Ju Lee Dae-Hwan Kim Dae-Kue Hwang Young-Woo Heo 《Current Applied Physics》2013,13(4):795-798
We have proposed dye-sensitized solar cells (DSSCs) with trench-type TiO2 nanotube structure to improve the low device efficiency of conventional TiO2 nanotube DSSCs using Ti substrate. Compared to the conventional standing-type TiO2 nanotube structure based DSSCs, the trench-type TiO2 nanotube structure based DSSCs have shown an improvement of device efficiency of approximately 40% due to the large increase of Jsc. In the trench-type TiO2 nanotube structure, the contact area between the TiO2 nanotube sidewall and the Ti substrate is significantly increased. This increase of contact area provides more charge transport paths than exist in the conventional standing-type TiO2 nanotube structure and reduces the electrical resistance between the Ti substrate and the TiO2 nanotubes. Therefore, the remarkable increase of Jsc is the result of the charge collection efficiency, which is improved due to the increase of contact area between the TiO2 nanotube sidewall and the Ti substrate in the trench-type TiO2 nanotube structure. The fabrication of the trench-type TiO2 nanotube structure is an effective manufacturing process for improving the device efficiency of TiO2 nanotube based DSSCs using Ti substrate. DSSCs having an 11.9 μm thick trench-type TiO2 nanotube structure have shown an efficiency of 5.74%. 相似文献
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Design optimization of high breakdown voltage vertical GaN junction barrier Schottky diode with high-K/low-K compound dielectric structure
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Kuiyuan Tian 《中国物理 B》2023,32(1):17306-017306
A vertical junction barrier Schottky diode with a high-$K$/low-$K$ compound dielectric structure is proposed and optimized to achieve a high breakdown voltage (BV). There is a discontinuity of the electric field at the interface of high-$K$ and low-$K$ layers due to the different dielectric constants of high-$K$ and low-$K$ dielectric layers. A new electric field peak is introduced in the n-type drift region of junction barrier Schottky diode (JBS), so the distribution of electric field in JBS becomes more uniform. At the same time, the effect of electric-power line concentration at the p-n junction interface is suppressed due to the effects of the high-$K$ dielectric layer and an enhancement of breakdown voltage can be achieved. Numerical simulations demonstrate that GaN JBS with a specific on-resistance ($R_{\rm on, sp}$) of 2.07 m$\Omega\cdot$cm$^{2}$ and a BV of 4171 V which is 167% higher than the breakdown voltage of the common structure, resulting in a high figure-of-merit (FOM) of 8.6 GW/cm$^{2}$, and a low turn-on voltage of 0.6 V. 相似文献
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Ti6Al7Nb has been used as an implant material because of its good corrosion resistance and high mechanical properties. However, the presence of aluminium (Al), which may lead to ostemalacia, anaemia and nervous system disorders, limited its wide clinical use. In this study, a titanium oxide (TiO2) nanoporous layer was fabricated on a Ti6Al7Nb alloy using an electrochemical anodic oxidation method. The structure of the TiO2 nanoporous layer was examined by scanning electron microscopy. The chemical compositions of the samples were analysed by X-ray photoelectron spectroscopy (XPS). Biocompatibility was evaluated by culturing rat osteoblast cells. The result showed that TiO2 nanoporous layers comprise a mixed oxide containing TiO2 and a small amount of nobium oxides (Nb2O5) and almost no elemental aluminium. The outer layer of the TiO2 nanoporous layer comprises highly ordered nanotubes and the inner layer forms disordered nanopores. The TiO2 nanoporous layer could support the adhesion, proliferation, differentiation and gene expression of osteoblast cells. Therefore, a TiO2 nanoporous layer could enhance the biocompatibility of Ti6Al7Nb alloy and is as a promising candidate for Ti6Al7Nb alloy implants. 相似文献
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Ming‐Zheng Wang Feng‐Xia Liang Biao Nie Long‐Hui Zeng Ling‐Xia Zheng Peng Lv Yong‐Qiang Yu Chao Xie Yang Yang Li Lin‐Bao Luo 《Particle & Particle Systems Characterization》2013,30(7):630-636
Schottky junctions made from a titanium dioxide nanotube (TiO2NT) array in contact with a monolayer graphene (MLG) film are fabricated and utilized for UV light detection. The TiO2NT array is synthesized by the anodization and the MLG through a simple chemical vapor deposition process. Photoconductive analysis shows that the fabricated Schottky junction photodetector (PD) is sensitive to UV light illumination with good stability and reproducibility. The corresponding responsivity (R), photoconductive gain (G), and detectivity (D*) are calculated to be 15 A W?1, 51, and 1.5 × 1012 cm Hz1/2 W?1, respectively. It is observed that the fabricated PD exhibits spectral sensitivity and a simple power‐law dependence on light intensity. Moreover, the height of the Schottky junction diode is derived to be 0.59 V by using a low temperature I–V measurement. Finally, the working mechanism of the TiO2NT array/MLG film Schottky junction PD is elucidated. 相似文献
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The capacitance-voltage(C-V) characteristic of the TiW/p-InP Schottky barrier diodes(SBDs) is analyzed considering the effects of the interface state(N_(ss)), series resistance(R_s), and deep level defects. The C-V of the Schottky contact is modeled based on the physical mechanism of the interfacial state and series resistance effect. The fitting coefficients α andβ are used to reflect the N_(ss) and R_s on the C-V characteristics, respectively. The α decreases with the increase of frequency,while β increases with the increase of frequency. The capacitance increases with the increase of α and the decrease of β.From our model, the peak capacitance and its position can be estimated. The experimental value is found to be larger than the calculated one at the lower voltage. This phenomenon can be explained by the effect of deep level defects. 相似文献
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J. Osvald 《Applied Physics A: Materials Science & Processing》2007,87(4):679-682
We report on a classical approach used to calculate energy band diagrams of AlGaN/GaN heterostructures. We were able to calculate the band diagram and carrier concentrations by this method also when the external bias was applied on the structure. The potential on the Schottky barrier side of the structure is defined more exactly than in a self-consistent solution of Poisson and Schrödinger equations. Dependence of the band profile and the carrier concentration of the two-dimensional gas on the piezoelectric charge can also be calculated by this approach. 相似文献
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This paper describes the fabrication and characteristics of the lateral Ti/4H-SiC Schottky barrier diodes (SBDs). SBDs are fabricated by nitrogen ion implantation into p-type 4H-SiC epitaxial layer. The implant depth profile is simulated using the Monte Carlo simulator TRIM. Measurements of the reverse I-V characteristics demonstrate a low reverse current, that is good enough for many SiC-based devices such as SiC metal-semiconductor field-effect transistors, and SiC static induction transistors. The parameters of the diodes are extracted from the forward I-V characteristics. The barrier height φ_b of Ti/4H-SiC is 0.95 eV. 相似文献
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Chuanxi Huang Kerong Zhu Mengyao Qi Yonglong Zhuang Chao Cheng 《Journal of Physics and Chemistry of Solids》2012,73(6):757-761
Bicrystal phase TiO2 nanotubes (NTS) containing monoclinic TiO2-B and anatase were prepared by the hydrothermal reaction of anatase nanoparticles with NaOH aqueous solution and a heat treatment. Their structure was characterized by XRD, TEM and Raman spectra. The results showed that the bicrystal phase TiO2 NTS were formed after calcining H2Ti4O9·H2O NTS at 573 K. The bicrystal phase TiO2 NTS exhibit significantly higher photocatalytic activity than the single phase anatase NTS and Dessuga P-25 nanoparticles in the degradation of Methyl Orange aqueous solution under ultraviolet light irradiation, which is attributed to the large surface and interface areas of the bicrystal phase TiO2 NTS. 相似文献
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Experimental and numerical analyses of high voltage 4H-SiC junction barrier Schottky rectifiers with linearly graded field limiting ring
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This paper describes the successful fabrication of 4H-SiC junction barrier Schottky(JBS) rectifiers with a linearly graded field limiting ring(LG-FLR). Linearly variable ring spacings for the FLR termination are applied to improve the blocking voltage by reducing the peak surface electric field at the edge termination region, which acts like a variable lateral doping profile resulting in a gradual field distribution. The experimental results demonstrate a breakdown voltage of 5 kV at the reverse leakage current density of 2 mA/cm2(about 80% of the theoretical value). Detailed numerical simulations show that the proposed termination structure provides a uniform electric field profile compared to the conventional FLR termination, which is responsible for 45% improvement in the reverse blocking voltage despite a 3.7% longer total termination length. 相似文献
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K. Xiao Y.Q. Liu P.A. Hu G. Yu W.P. Hu D.B. Zhu X.Y. Liu H.M. Liu D.X. Wu 《Applied Physics A: Materials Science & Processing》2006,83(1):53-56
Electrical transport properties of a Schottky junction consisting of carbon nanotube and nitrogen-doped carbon nanotube were studied. The current-voltage characteristics of the junction exhibited reproducible rectifying behavior which could be explained by the Schottky barrier junction. The barrier height and the ideal factor were determined by fitting the current-voltage characteristics to the generalized diode equation. A near power-law dependence of I∼Vm was observed, where the exponent m increases with decreasing temperature. This effect can be accounted for by filling of deep traps at lower temperatures. The charge transport in the nanotubes is found to be strongly controlled and limited by the highly defective trap state originated from structural and chemical defects due to the doping of nitrogen in the CNx nanotube part. PACS 73.63.Fg; 73.63.Rt; 85.30.Kk 相似文献
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The preparation and characterization of nanoparticle TiO2/Ti films and their photocatalytic activity
《Journal of Physics and Chemistry of Solids》2003,64(4):615-623
Nanoparticle TiO2/Ti films were prepared by a sol–gel process using Ti(OBu)4 as raw material, the as-prepared film samples were also characterized by TG-DTA, XRD, TEM, SEM, XPS, DRS, PL, SPS and EFISPS testing techniques. TiO2 nanoparticles experienced two processes of phase transition, i.e. amorphous to anatase and anatase to rutile at the calcining temperature range from 450 to 700 °C. TiO2 nanoparticles calcined at 600 °C had similar composition, structure, morphology and particle size with the internationally commercial P-25 TiO2 particles. Thus, the conclusion that 600 °C might be the most appropriate calcining temperature during the preparation process of nanoparticle TiO2/Ti film photocatalysts could be made by considering the main factors such as the properties of TiO2 nanoparticles, the adhesion of nanoparticle TiO2 film to Ti substrate, the effects of calcining temperature on Ti substrate and the surface characteristics and morphology of nanoparticle TiO2/Ti film for the practice view. The Ti element mainly existed on the nanoparticle TiO2/Ti(3) film calcined at 600 °C as the chemical state of Ti4+, while O element mainly existed as three kinds of chemical states, i.e. crystal lattice oxygen, hydroxyl oxygen and adsorbed oxygen with increasing band energy. Its photoluminescence (PL) spectra with a peak at about 380 nm could be observed using 260 nm excitation, possibly resulting from the electron transition from the bottom of conduction band to the top of valence band. The PL peak position was nearly the same as the onset of its diffuse reflection spectra (DRS) and surface photovoltage spectroscopy (SPS), demonstrating that the effects of the quantum size on optical property were greater than that of the Coulomb and surface polarization. The PL spectra with two peaks related to the anatase and rutile, respectively, could be observed using the excited wavelength of 310 nm. Weak PL spectra could be observed using the excited wavelength of 450 nm, resulting from surface states. In addition, during the experimental process of the photocatalytic degradation phenol, the photocatalytic activity of nanoparticle TiO2/Ti film with three layers calcined at 600 °C was the highest. 相似文献
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Effect of graphene tunnel barrier on Schottky barrier height of Heusler alloy Co_2MnSi/graphene/n-Ge junction
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We demonstrate that the insertion of a graphene tunnel barrier between Heusler alloy Co_2MnSi and the germanium(Ge) channel modulates the Schottky barrier height and the resistance–area product of the spin diode. We confirm that the Fermi level is depinned and a reduction in the electron Schottky barrier height(SBH) occurs following the insertion of the graphene layer between Co_2MnSi and Ge. The electron SBH is modulated in the 0.34 eV–0.61 eV range. Furthermore,the transport mechanism changes from rectifying to symmetric tunneling following the insertion. This behavior provides a pathway for highly efficient spin injection from a Heusler alloy into a Ge channel with high electron and hole mobility. 相似文献
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对Ti/6H-SiC Schottky结的反向特性进行了测试和理论分析,提出了一种综合的包括SiC Schottky结主要反向漏电流产生机理的反向隧穿电流模型,该模型考虑了Schottky势垒不均匀性、Ti/SiC界面层电压降和镜像力对SiC Schottky结反向特性的影响,模拟结果和测量值的相符说明了以上所考虑因素是引起SiC Schottky结反向漏电流高于常规计算值的主要原因.分析结果表明在一般工作条件下SiC Schottky结的反向特性主要是由场发射和热电子场发射电流决定的. 相似文献
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基于热电子发射和热电子场发射模式,利用I-V方法研究了Pt/Au/n-InGaN肖特基接触的势垒特性和电流输运机理,结果表明,在不同背景载流子浓度下,Pt/Au/n-InGaN肖特基势垒特性差异明显.研究发现,较低生长温度制备的InGaN中存在的高密度施主态氮空位(VN)缺陷导致背景载流子浓度增高,同时通过热电子发射模式拟合得到高背景载流子浓度的InGaN肖特基势垒高度和理想因子与热电子场发射模式下的结果差别很大,表明VN缺陷诱发了隧穿机理并降低了肖特基势垒高度,相应的隧穿电流显著增大了肖特基势垒总的输运电流,证实热电子发射和缺陷辅助的隧穿机理共同构成了肖特基势垒的电流输运机理.低背景载流子浓度的InGaN肖特基势垒在热电子发射和热电子场发射模式下拟合的结果接近一致,表明热电子发射是其主导的电流输运机理. 相似文献
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以商用金红石相TiO2粉末为原料,通过在碱性溶液中150℃水热48h的方法合TiO2纳米管.采用SEM,TEN,XRD分析手段对TiO2纳米管的形貌和结构演变进行了表征.制成的TiO2纳米管与TritonX-100,乙酰丙酮混合后,通过丝网印刷的方法涂敷到ITO导电玻璃衬底上,并且在450℃下烧结30min后得到可应用于染料敏化太阳电池的多孔光阳极.将此光阳极浸泡于N719染料敏化后,与镀铂对电极组装电池,两者之间灌入液态电解质,电池的有效面积为0.28 cm2.在标准氙灯模拟器下(AM 1.5,100 roW/cm2)测试r电池的J-V特性,得到2.17%的光电转换效率. 相似文献
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《Journal of Physics and Chemistry of Solids》2014,75(4):505-511
Ag-doping TiO2 composite nanotubes (Ag-TNTs) were synthesized by alkaline fusion followed by hydrothermal treatment. The microstructure and morphology of the materials were characterized by XRD, TEM, XPS, SPS (surface photovoltage spectroscopy), FISPS (electric field-induced surface photovoltage spectroscopy) and Raman spectroscopy. First-principles calculations based on density-functional theory (DFT) showed the formation of several impurity levels near the top of the valence band in the band gap (Eg) of rutile TiO2 due to Ag doping. A “double junction” is proposed, involving a Schottky junction and p–n junction (denoted as “Ag-p–n junction”) occurring between the Ag particles and the nanotube surface, as well as forming inside TiO2 nanotubes, respectively. The strongly built-in electric field of the junctions promotes the separation of photo-holes and photoelectrons, enhancing the photocatalytic efficiency. XRD results indicated that the composite Ag-TNTs exist as a mixture of anatase and rutile phases. XPS results showed that Ti4+ is the primary state of Ti. Raman spectral analysis of Ag-TNTs revealed the presence of a new peak at 271 cm−1. The red-shift of the absorption light wavelength of Ag-TNTs was 0.16 eV (20 nm) due to a considerable narrowing of Eg by the existing impurity levels. 相似文献