Demonstration and modeling of unipolar-carrier-conduction GaN Schottky-pn junction diode with low turn-on voltage

By introducing a thin p-type layer between the Schottky metal and n-GaN layer, this work presents a Schottky-pn junction diode(SPND) configuration for the GaN rectifier fabrication. Specific unipolar carrier conduction characteristic is demonstrated by the verification of temperature-dependent current–voltage(I–V) tests and electroluminescence spectra.Meanwhile, apparently advantageous forward conduction properties as compared to the pn diode fabricated on the same wafer have been achieved, featuring a lower turn-on voltage of 0.82 V. Together with the analysis model established in the GaN SPND for a wide-range designable turn-on voltage, this work provides an alternative method to the GaN rectifier strategies besides the traditional solution.

An Improved DITC Control Method Based on Turn-on Angle Optimization

Switched reluctance motor(SRM)usually adopts Direct Instantaneous Torque Control(DITC)to suppress torque ripple.However,due to the fixed turn-on angle and the control mode of the two-phase exchange region,the conventional DITC control method has low adaptability in different working conditions,which will lead to large torque ripple.For this problem,an improved DITC control method based on turn-on angle optimization is proposed in this paper.Firstly,the improved BP neural network is used to construct a nonlinear torque model,so that the torque can be accurately fed back in real time.Secondly,the turn-on angle optimization algorithm based on improved GRNN neural network is established,so that the turn-on angle can be adjusted adaptively online.Then,according to the magnitude of inductance change rate,the two-phase exchange region is divided into two regions,and the phase with larger inductance change rate and current is selected to provide torque in the sub-regions.Finally,taking a 3-phase 6/20 SRM as example,simulation and experimental verification are carried out to verify the effectiveness of this method.

基于水杨醛的Turn-on型铝离子荧光探针的研究

Al^(3+)的摄入量过多,会对人的神经系统造成极大破坏,导致痴呆,骨萎缩等病症.本研究利用水杨醛与Al^(3+)形成金属配合物,作为Turn-on型荧光探针实现对Al^(3+)的快速检测.该荧光探针对Al^(3+)具有高灵敏性和选择性,在Al^(3+)浓度为0~14μM的区间内,相对荧光强度与Al^(3+)的浓度呈现良好的线性关系(R^2=0.998 43),其检测限为0.16μM.

Shortening turn-on delay of SiC light triggered thyristor by7-shaped thin n-base doping profile

A new 4 H–SiC light triggered thyristor（LTT） with 7-shaped thin n-base doping profile is proposed and simulated using a two-dimensional numerical method. In this new structure, the bottom region of the thin n-base has a graded doping profile to induce an accelerating electric field and compensate for the shortcoming of the double-layer thin n-base structure in transmitting injected holes. In addition, the accelerating electric field can also speed up the transmission of photongenerated carriers during light triggering. As a result, the current gain of the top pnp transistor of the SiC LTT is further increased. According to the TCAD simulations, the turn-on delay time of the SiC LTT decreases by about 91.5% compared with that of previous double-layer thin n-base SiC LTT. The minimum turn-on delay time of the SiC LTT is only 828 ns,when triggered by 100 mW/cm^2 ultraviolet light. Meanwhile, there is only a slight degradation in the forward blocking characteristic.

超快速turn-on型ClO^(-)荧光探针的合成及性能

为实现次氯酸根的实时、快速、便捷检测,我们以2,7-二溴-9-芴酮为原料,通过两步常规反应,合成了一种新型的turn-on型ClO^(-)荧光探针。在磷酸缓冲盐溶液(PBS)中,随着ClO^(-)浓度的增大,探针在511 nm的发射峰逐渐增大,呈绿色荧光发射。探针与ClO^(-)反应迅速,10 s内反应完成。此外,该探针对ClO^(-)有较低的检出限,检出限为0.74μmol·L^(-1)。细胞实验表明探针可以在细胞水平检测内源性和外源性的ClO^(-)。

基于肉桂酰肼的Zn^(2+)、Mg^(2+)和Cd^(2+)Turn-On型荧光探针研究

本文以肉桂酸甲酯、水合肼及水杨醛为原料,设计合成了一种“turn-on”型离子选择性荧光探针,采用NMR、IR及HRMS对其结构进行了表征,结果表明该探针为N'-[(2-羟苯基)亚甲基]-3-{2-[(2-羟苯基)亚甲基]肼-1-基}-3-苯丙酰肼(ZL)。基于其存在的酰基和邻羟苯基亚甲基胺结构,研究了其对不同金属离子的识别作用,结果Zn^(2+)、Mg^(2+)和Cd^(2+)对探针ZL荧光表现出“turn-on”效应,其荧光分别增强了47、21、24倍,而其他金属离子对其荧光光谱及强度无影响,化合物ZL表现出对Zn^(2+)、Mg^(2+)和Cd^(2+)的高选择性识别和高灵敏检测,其检出限分别为5.5nmol·L^(-1)、8.4nmol·L^(-1)、9.9 nmol·L^(-1)。通过Job s plot实验表明ZL与Zn^(2+)、Mg^(2+)和Cd^(2+)的结合比为1∶1,结合核磁滴定及Gaussian计算结果,可推测Zn^(2+)和Cd^(2+)与ZL的酚羟基结合;Mg^(2+)与ZL中的酚羟基、羰基氧及席夫碱的氮原子结合。本文设计的荧光探针ZL可望实现对Zn^(2+)、Mg^(2+)、Cd^(2+)的快速高灵敏检测,在生物以及环境样本的监测中具有较好的应用前景。

Preparation of multicolor carbon dots with thermally turn-on fluorescence for multidimensional information encryption

Carbon dots(CDs)with superior fluorescence properties have attracted a growing number of research interests in anti-counterfeiting.However,the preparation of CDs with thermally turn-on fluorescence and full-color-emitting in visible spectrum is still a big challenge due to the complicated reaction mechanism in the formation of CDs.Here,a simple precursor-oriented strategy for the preparation of multicolor CDs with heat-stimuli turn-on fluorescence is reported.Comprehensive experimental characterizations and theoretical calculations revealed that the emission wavelength of CDs can be readily tuned from 460 nm to 654 nm with selected precursors,which was ascribed to the extent of conjugated sp2-domains(core states)and the amount of oxygen-and nitrogen-containing groups bound to sp2-domains(surface states).After simply mixing two or three kinds of CDs,a full-color range of fluorescence emission was realized,and the CDs-based fluorescence inks were successfully fabricated.Particularly,all the printed patterns from the inkjet exhibited a thermal-induced enhancement in fluorescence.On this basis,combining CDs with heating-induced“turn-off”fluorescence materials can lead to multidimensional and multistage encryption.These results demonstrate that the thermochromic and photochromic CDs with much more enhanced security exhibit promising application in data storage and encryption.

Turn-on fluorescence detection of specific inorganic anions by Zr(Ⅳ)-MOF with amino-functional group

Inorganic anions such as phosphates and carbonates are essential in the natural system and it is important for the detec-tion of such species.In this work,the fluorescence sensing capacity of Zr(IV)framework with an amino-functional group,namely UiO-66-NH_(2),towards specific inorganic anions was investigated in aqueous media.The results revealed that the fluorescence emission intensity of UiO-66-NH2 could be strongly enhanced by phosphate and carbonate anions including HPO_(4)^(2-),H_(2)PO_(4)^(-),PO_(4)^(3-),P_(2)O_(7)^(4-),HCO_(3)^(-)and CO_(3)^(2-),implying its sensing capacity towards phosphate and carbonate anions.Furthermore,fluorescence titration experiments exhibit that the emission intensity enhancement ratio depends linearly on the concentration of anions,suggesting the possibility of quantitative detection of these anions.Further studies suggest that the sensing of UiO-66-NH,towards HPO_(4)^(2-)/PO_(4)^(3-)/P_(2)O_(4)^(-)/HCO_(3)^(-)/CO_(2)-could be ascribed to the collapse of the framework,while that for H_(2)PO_(4)-could be attributed to the adsorption of H,PO4-by UiO-66-NH2 with hydrogen bonding interactions between H,PO4-and the amino group of UiO-66-NH_(2) supported by the different fluorescence response of UiO-66 and UiO-66-NH,towards the anions.

Turn-on型汞(Ⅱ)荧光探针的制备及性能研究

以罗丹明B为识别基团,设计并合成了一种Turn-on型Hg2+荧光探针1,与Hg2+络合后荧光显著增强,溶液颜色由浅黄色变为粉色,从而实现了对Hg2+的快速检测。Hg2+含量在1~7μmol/L范围内,580 nm处荧光强度与Hg2+浓度呈良好的线性关系(R=0.9982)。探针1对Hg2+的检出限为34 pmol/L,常见的其它8种金属离子的存在对Hg2+的检测无明显干扰。

《孟子·离娄上》“反其仁”章析论

《孟子·离娄上》“反其仁”章单章研究包括分析、综论两个层面。从分析的层面看,直面当下困境,把控所有困局,构成第一、二节的群己之辨;“永言配命,自求多福”,构成第三节的力命之辨;唯有经由力命之辨,群己之辨方能达成自身的和谐。从综论的层面看,以“反求诸己”为功夫,可谓传孔子、曾子之说;以“天下归之”为功效,可谓“承上章而言”;基于群己之辨与力命之辨的内在张力,当以“反求诸己”为切要。孟子的“反求诸己”之思,历史影响深远,当代价值显著。

Increasing substrate resistance to improve the turn-on uniformity of a high-voltage multi-finger GG-nLDMOS

With the impact of the non-uniform turn-on phenomenon,the ESD robustness of high-voltage multifinger devices is limited.This paper describes the operational mechanism of a GG-nLDMOS device under ESD stress conditions and analyzes the reason that causes the non-uniform turn-on characteristics of a multi-finger GGnLDMOS device.By means of increasing substrate resistance,an optimized device structure is proposed to improve the turn-on uniformity of a high-voltage multi-finger GG-nLDMOS.This approach has been successfully verified in a 0.35 m 40 V BCD process.The TLP test results reveal that increasing the substrate resistance can effectively enhance the turn-on uniformity of the 40 V multi-finger GG-nLDMOS device and improve its ESD robustness.

CsPbBr_(x)I_(3-x)thin films with multiple ammonium ligands for low turn-on pure-red perovskite light-emitting diodes

All-inorganic α-CsPbBr_(x)I_(3-x)perovskites featuring nano-sized crystallites show great potential for pure-red light-emitting diode(LED)applications.Currently,the CsPbBr_(x)I_(3-x)LEDs based on nano-sized α-CsPbBr_(x)I_(3-x)crystallites have been fabricated mainly via the classical colloidal route including a tedious procedure of nanocrystal synthesis,purification,ligand or anion exchange,film casting,etc.With the usually adopted conventional LED device structure,only high turn-on voltages(>2.7)have been achieved for CsPbBrxl3-x LEDs.Moreover,this mix-halide system may suffer from severe spectra-shift under bias.In this report,CsPbBr_(x)I_(3-x)thin films featuring nano-sized crystallites are prepared by incorporating multiple ammonium ligands in a one-step spin-coating route.The multiple ammonium ligands constrain the growth of CsPbBr_(x)I_(3-x)nanograins.Such CsPbBr_(x)I_(3-x)thin films benefit from quantum confinement.The corresponding CsPbBr_(x)I_(3-x)LEDs,adopting a conventional LED structure of indium-doped tin oxide(ITO)/poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate)(PEDOT:PSS)/CsPbBr_(x)I_(3-x)/[6,6]-phenyl C61 butyric acid methyl ester(PCBM)/bathocuproine(BCP)/AI,emit pure-red color at Commission Internationale de I'eclairage(CIE)coordinates of(0.709,0.290),(0.711,0.289),etc.,which represent the highest color-purity for reported pure-red perovskite LEDs and meet the Rec.2020 requirement at CIE(0.708,0.292)very well.The CsPbBr_(x)I_(3-x)LED shows a low turn-on voltage of 1.6 V,maximum external quantum efficiency of 8.94%,high luminance of 2,859 cd·m^(-2),and good color stability under bias.

A Sensitive Fluorescent Turn-on Probe NapP-deap Based on Naphthalimide Derivative to Detect Hg(II) Ions in HEPES Buffer Solution and Living Cells

A highly sensitive fluorescent“turn-on”probe NapP-deap based on naphthalimide derivative was developed that bound Hg^2+ ions rapidly in the N-2-hydroxyethylpiperazine-N-ethane-sulphonic acid(HEPES)buffer solution via photo-induced electron transfer(PET)being inhibited mechanism.The titration experiment displayed that the emission intensity of NapP-deap at 540 nm was almost linearly increased by about 3-fold.The Job’s plot showed a stoichiometry factor of 1:1 of the ligand-to-metal ratio.The detection limit of fluorescent probe was calculated to be 6.2×10^?9 mol/L.^1H NMR studies could confirm that one Hg^2+ ion was bound by the N atoms(a,b)of piperazine or the N atom(c)of pyridine.The fluorescent probe could be used for the detection of Hg^2+ ions in living cells.

Enzyme-Triggered Fluorescence Turn-on： A Probe for Specifically Imaging Ovarian-Cancer-Related γ-Glutamyltranspeptidase

A fluorescent turn-on probe for specifically targeting γ-glutamyltranspeptidase （GGT） was designed and synthe- sized by integrating boron-dipyrromethene （BODIPY） as a chromophore and glutathione （GSH） as the GGT sub- strate. GGT-catalyzed the cleavage of the γ-glutamyl bond and generated the aromatic hydrocarbon transfer between the sulfur and the nitrogen atom in BODIPY, leading to distinct optical changes. Such specific responsiveness pro- vides an easily distinguishable fluorescence signal to visualize the GGT activity in living cells and differentiate GGT-positive cancer cells from GGT-negative cells.

A New Thioimide-Based Fluorescent ＇Turn-On＇ and Chromogenic Chemodosimeter in Acetonitrile and Its Nanoparticles in Water for Highly Selective and Sensitive Detection of Hg^2＋

A new thioimide-based fluorescent ‘turn-on’ and chromogenic chemodosimeter for highly selective and sensitive detection of Hg^2＋ has been developed. The dual response of Hg^2＋ was not only in the marked color change of the solution from dark green to colorless, but also in the significant enhancement of the fluorescent intensity of the chemodosimeter in aqueous acetonitrile. Moreover, when the chemodosimeter was assembled into nanoparticles, it could also exhibit remarkably dual response of color change and fluorescence enhancement for detection of Hg^2＋.

A novel DTSCR with a variation lateral base doping structure to improve turn-on speed for ESD protection

The turn-on speed of electrostatic discharge （ESD） protection devices is very important for the protection of the ultrathin gate oxide. A double trigger silicon controlled rectifier device （DTSCR） can be used effectively for ESD protection because it can turn on relatively quickly. The turn-on process of the DTSCR is first studied, and a formula for calculating the turn-on time of the DTSCR is derived. It is found that the turn-on time of the DTSCR is determined mainly by the base transit time of the parasitic p-n-p and n-p-n transistors. Using the variation lateral base doping （VLBD） structure can reduce the base transit time, and a novel DTSCR device with a VLBD structure （VLBD_DTSCR） is proposed for ESD protection applications. The static-state and turn-on characteristics of the VLBD DTSCR device are simulated. The simulation results show that the VLBD structure can introduce a built-in electric field in the base region of the parasitic n-p-n and p--n-p bipolar transistors to accelerate the transport of free-carriers through the base region. In the same process and layout area, the turn-on time of the VLBD DTSCR device is at least 27% less than that of the DTSCR device with the traditional uniform base doping under the same value of the trigger current.

Direct identification of HMX via guest-induced fluorescence turn-on of molecular cage

Octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine(HMX) is one of the most widely used powerful explosives. The direct and selective detection of HMX, without the requirement of specialized equipment, remains a great challenge due to its extremely low volatility, unfavorable reduction potential and lack of aromatic rings. Here, we report the first chemical probe of direct identification of HMX at ppb sensitivity based on a designed metal-organic cage(MOC). The cage features two unsaturated dicopper units and four electron donating amino groups inside the cavity, providing multiple binding sites to selectively enhance host-guest events. It was found that compared to other explosive molecules the capture of HMX inside the cavity would strongly modulate the emissive behavior of the host cage, resulting in highly induced fluorescence “turn-on”(160 folds). Based on the density functional theory(DFT) simulation, the mutual fit of both size and binding sites between host and guest leads to the synergistic effects that perturb the ligand-to-metal charge-transfer(LMCT) process, which is probably the origin of such selective HMX-induced turn-on behavior.

Turn-on and turn-off voltages of an avalanche p-n junction

Characteristics of the turn-on and turn-off voltage of avalanche p-n junctions were demonstrated and studied. As opposed to existing reports, the differences between the turn-on and turn-offvoltage cannot be neglected when the size of the p-n junction is in the order of microns. The difference increases inversely with the area of a junction, exerting significant influences on characterizing some parameters of devices composed of small avalanche junctions. Theoretical analyses show that the mechanism for the difference lies in the increase effect of the threshold multiplication factor at the turn-on voltage of a junction when the area of a junction decreases. Moreover, the ＂breakdown voltage＂ in the formula of the avalanche asymptotic current is, in essence, the avalanche turn-off voltage, and consequently, the traditional expression of the avalanche asymptotic current and the gain of a Geiger mode avalanche photodiode were modified.

Highly selective and turn-on fluorescence probe with red shift emission for naked-eye detecting Al^(3+)and Ga^(3+)based on metal-organic framework

A novel ZnII-based metal-organic framework with the formula of{[Zn_(2)(BBIP)_(2)(NDC)_(2)]·H_(2)O}n(JXUST-5)derived from 3,5-bis(benzimidazol-1-yl)pyridine(BBIP)and 1,4-naphthalenedicarboxylic acid(H_(2)NDC)has been synthesized.The adjacent Zn^(II)ions are linked through two BBIP ligands to form a[Zn_(2)(BBIP)_(2)]secondary building unit(SBU).The neighbouring SBUs are further connected by NDC^(2-)withμ2-η^(1):η^(1)andμ2-η^(1):η^(1):η^(1)bridging modes to form a two-dimensional(2D)framework.Topological analysis shows that JXUST-5 could be simplified as an uninodal fes topology with a point symbol of{4.8^(2)}.Furthermore,the 2D framework net could be extended through C-H···πinteraction to form the three-dimensional supramolecular structure.Luminescent experiments suggest that JXUST-5 could selectively and sensitively recognize Al^(3+)and Ga^(3+)through fluorescence enhancement effect along with a relatively large red shift.The detection limits for Al^(3+)and Ga^(3+)are 0.17 and 0.69 ppm,respectively.Interestingly,the sensing process for both Al^(3+)and Ga^(3+)could be directly observed with naked eyes under 365 nm UV lamp.Notably,JXUST-5 could be recycled at least five times as a fluorescent sensor toward Al^(3+)and Ga^(3+),which is the second example of turn-on MOF based fluorescent sensor toward Ga^(3+).

基于苯并[b]萘并[1,2-d]噻吩的可见光驱动光环化荧光turn-on型二芳基乙烯的合成与性能研究

可见光驱动光环化的荧光turn-on型二芳基乙烯分子开关是超分辨显微成像的理想材料,但目前关于该类型分子的报道仍较少.本工作合成了一种基于苯并[b]萘并[1,2-d]噻吩(BNTP)的405 nm可见光驱动光环化的荧光turn-on型二芳基乙烯分子BNTP-BTTO4,同时系统研究了该分子的光物理性能与稳定性,并借助密度泛函理论(DFT)计算厘清了分子实现可见光驱动光环化及荧光turn-on原因.另外,本研究发现BNTP引入后分子表现出比参比分子Ph-BTTO4更优异的抗疲劳性、热稳定性和光稳定性,尤其是在历经200 min 405 nm可见光照射后,BNTP-BTTO4(c)吸收强度只下降4%,光稳定性大幅提升.本研究为设计开发性能优异的可见光驱动光环化的荧光turn-on型二芳基乙烯提供了新的思路.