Low voltage n-type OFET based on double insulators

A top contact n-type organic field-effect transistor with low operating voltage was fabricated by employing Ta2O5/PMMA as the double insulators and PTCDI-Cl2 as the semiconductor active layer. The Ta2O5 layer was prepared by using simple economical anodization technique and the PMMA layer was prepared by using the spin-coating method. Compared with the OFET with single Ta2O5 insulator, the device with double insulators shows obviously better electrical performance. It has a field effect electron mobility of 0.063 cm^2/Vs, an on/off ratio of 1.7 × 10^4 and a threshold voltage of 2.3 V.     

Characterization of CdMnTe radiation detectors using current and charge transients

Charge transport characteristics of Cd_0.95Mn_0.05Te:In radiation detectors have been evaluated by combining time resolved current transient measurements with time of flight charge transient measurements.The shapes of the measured current pulses have been interpreted with respect to a concentration of net positive space-charge, which has resulted in an electric field gradient across the detector bulk.From the recorded current pulses the charge collection efficiency of the detector was found to approach 100%.From the evolution of the charge collection efficiency with applied bias,the electron mobility-lifetime product ofμ_nτ_n =（8.5±0.4）×10^-4 cm²/V has been estimated.The electron transit time was determined using both transient current technique and time of flight measurements in the bias range of 100-1900 V.From the dependence of drift velocity on applied electric field the electron mobility was found to beμ_n =（718±55） cm²/（V·s） at room temperature.     

Electrical and γ-ray energy spectrum response properties of PbI2 crystal grown by physical vapor transport

Lead iodide single crystal was grown by physical vapor transport method.Two radiation detectors with different configurations were fabricated from the as-grown crystal.The electrical and y-ray response properties at room temperature of the both detectors were investigated.It is found that the dark resistivity of the detectors are respectively 3×10¹⁰Ω·cm for bias electric field parallel to crystal c-axis（E//c） and 2×10⁸Ω·cm for perpendicular to crystal c-axis（E⊥c）.The energy spectrum response measurement shows that both detectors were sensitive to ²⁴¹ Am 59.5 keVγ-rays,and achieved a good energy resolution of 16.8%for the E⊥c-axis configuration detector with a full width at half maximum of 9.996 keV.     

Multisubband electron mobility in a parabolic quantum well structure under the influence of an applied electric field

We study the multisubband electron mobility in a barrier delta doped AlχGal-χAs parabolic quantum well structure under the influence of an applied electric field perpendicular to the interface plane. We consider the alloy fraction χ = 0.3 for barriers and vary x from 0.0 to 0.1 for the parabolic well. Electrons diffuse into the well and confine within the triangular like potentials near the interfaces due to Coulomb interaction with ionized donors. The parabolic structure potential, being opposite in nature, partly compensates the Coulomb potential. The external electric field further amends the potential structure leading to an asymmetric potential profile. Accordingly the energy levels, wave functions and occupation of subbands change. We calculate low temperature electron mobility as a function of the electric field and show that when two subbands are occupied, the mobility is mostly dominated by ionised impurity scattering mediated by intersubband effects. As the field increases transition from double subband to single subband occupancy occurs. A sudden enhancement in mobility is obtained due to curtailment of intersubband effects. Thereafter the mobility is governed by both impurity and alloy disorder scatterings. Our analysis of mobility as a function of the electric field for different structural parameters shows interesting results.     

Low voltage n-type OFET based on double insulators

A top contact n-type organic field-effect transistor with low operating voltage was fabricated by employing Ta2O5/PMMA as the double insulators and PTCDI-C12 as the semiconductor active layer. The Ta2O5 layer was prepared by using simple economical anodization technique and the PMMA layer was prepared by using the spin-coating method. Compared with the OFET with single Ta2O5 insulator,the device with double insulators shows obviously better electrical performance. It has a field effect electron mobility of 0.063 cm2/Vs,an on/off ratio of 1.7×104 and a threshold voltage of 2.3 V.     

Linear x-ray detector array made on bulk CdZnTe for 30∼100 keV energy

A CdZnTe detector grown by the high pressure Bridgman (HPB) growth technique was tested using high energy x-rays (30∼100 keV), and the performance was compared with a commercially available Nal scintillating detector of 5 cm thickness. The charge collection efficiency of a CdZnTe detector is as high as 90% at relatively low electric field, 600 V/cm. At high x-ray photon energies, the detection efficiency is reduced due to the thickness of the CdZnTe. A 32 channel linear array was fabricated on 1.2∼1.7 mm thick CdZnTe, of which the detector area was 175 × 800 μm² and the pitch size 250 μm. The measured dark current for the 16 element detector was as low as 0.1 pA at 800 V/cm with an excellent uniformity. Energy spectra were measured using a Co⁵⁷ radiation source. A small pixel effect and charge sharing were observed. The energy resolution was improved and compared with the large area detector. The array detector gave an average 5.8% full-width-half-maximum (FWHM) at 122 keV photopeak. The large area detector of the same material before fabrication exhibited a low energy tail at the photopeak, which limits the photopeak FWHM to 8%.     

RF-MBE Grown AlGaN/GaN HEMT Structure with High Al Content

A Si doped AlGaN/GaN HEMT structure with high Al content (x=43%) in the barrier layer is grown on sapphire substrate by RF-MBE.The structural and electrical properties of the heterostructure are investigated by the triple axis Xray diffraction and Van der PauwHall measurement,respectively.The observed prominent Bragg peaks of the GaN and AlGaN and the Hall results show that the structure is of high quality with smooth interface.The high 2DEG mobility in excess of 1260cm2／（V·s） is achieved with an electron density of 1.429e13cm－2 at 297K,corresponding to a sheet-densitymobility product of 1.8e16V－1·s－1.Devices based on the structure are fabricated and characterized.Better DC characteristics,maximum drain current of 1.0A/mm and extrinsic transconductance of 218mS/mm are obtained when compared with HEMTs fabricated using structures with lower Al mole fraction in the AlGaN barrier layer.The results suggest that the high Al content in the AlGaN barrier layer is promising in improving material electrical properties and device performance.     

An analytical model for the surface electrical field distribution of LDMOSFETs with shield rings

An analytical model of an LDMOSFET with a shield ring is established according to the 2D Poisson equation.Surface electrical field distribution along the drift region is obtained from this model and the influence of shield length and oxide thickness on the electrical field distribution is studied.The robustness of this model is verified using ISE TCAD simulation tools.The breakdown voltage of a specific device is also calculated and the result is in good agreement with experimental data.     

基于插入WO3缓冲层并五苯有机场效应晶体管性能的研究

The pentacene-based organic field effect transistor （OFET） with a thin transition metal oxide （WO3） layer between pentacene and metal （AI） source/drain electrodes was fabricated. Compared with conventional OFET with only metal AI source/drain electrodes, the introduction of the WO3 buffer layer leads to the device performance enhancement. The effective field-effect mobility and threshold voltage are improved to 1.90 em2/（V.s） and 13 V, respectively. The performance improvements are attributed to the decrease of the interface energy barrier and the contact resistance. The results indicate that it is an effective approach to improve the OFET performance by using a WO3 buffer layer.     

Growth and characterization of 2-inch high quality β-Ga2O3 single crystals grown by EFG method

β-Ga2O3 is an ultra-wide band-gap semiconductor with promising applications in UV optical detectors,Schottky barrier diodes,field-effect transistors and substrates for light-emitting diodes.However,the preparation of large β-Ga2O3 crystals is undeveloped and many properties of this material have not been discovered yet.In this work,2-inch β-Ga2O3 single crystals were grown by using an edge-defined film-fed growth method.The high quality of the crystal has been proved by high-resolution X-ray diffraction with 19.06 arcsec of the full width at half maximum.The electrical properties and optical properties of both the unintentionally doped and Si-doped β-Ga2O3 crystals were investigated systematically.     

Theoretical analysis of the relationship between the Brillouin gain coefficient and the strain in the optical-fiber sensors

The relation between the power of the Brillouin signal and the strain is one of the bases of the distributed fiber sensors of temperature and strain. The coefficient of the Bfillouin gain can be changed by the temperature and the strain that will affect the power of the Brillouin scattering. The relation between the change of the Brillouin gain coefficient and the strain is thought to be linear by many researchers. However, it is not always linear based on the theoretical analysis and numerical simulation. Therefore, errors will be caused if the relation between the change of the Brillouin gain coefficient and the strain is regarded as to be linear approximately for measuring the temperature and the strain. For this reason, the influence of the parameters on the Brillouin gain coefficient is proposed through theoretical analysis and numerical simulation.     

An improved parallel thinning algorithm with two subiterations

The parallel thinning algorithm with two subiterations is improved in this paper. By analyzing the notions of connected components and passes, a conclusion is drawn that the number of passes and the number of eight-connected components are equal. Then the expression of the number of eight-connected components is obtained which replaces the old one in the algorithm. And a reserving condition is proposed by experiments, which alleviates the excess deletion where a diagonal line and a beeline intersect. The experimental results demonstrate that the thinned curve is almost located in the middle of the original curve connectivelv with single pixel width and the processing speed is high.     

Resolution Enhancement Technology:Integrated Process Solutions using OPC

DUV lithography, using the 248 nm wavelength, is a viable manufacturing option for devices with features at 130 nm and less. Given the low kl value of the lithography, integrated process development is a necessary method for achieving acceptable process latitude. The application of assist features for rule based OPC requires the simultaneous optimization of the mask, illumination optics and the resist.Described in this paper are the details involved in optimizing each of these aspects for line and space imaging.A reference pitch is first chosen to determine how the optics will be set. The ideal sigma setting is determined by a simple geometrically derived expression. The inner and outer machine settings are determined, in turn,with the simulation of a figure of merit. The maximum value of the response surface of this FOM occurs at the optimal sigma settings. Experimental confirmation of this is shown in the paper.Assist features are used to modify the aerial image of the more isolated images on the mask. The effect that the diffraction of the scattering bars (SBs) has on the image intensity distribution is explained. Rules for determining the size and placement of SBs are also given.Resist is optimized for use with off-axis illumination and assist features. A general explanation of the material' s effect is discussed along with the affect on the through-pitch bias. The paper culminates with the showing of the lithographic results from the fully optimized system.     

Study of waveguide coupling efficiency in hybrid silicon lasers

This paper presents a new method to increase the waveguide coupling efficiency in hybrid silicon lasers. We find that the propagation constant of the InGaAsP emitting layer can be equal to that of the Si resonant layer through improving the design size of the InP waveguide. The coupling power achieves 42% of the total power in the hybrid lasers when the thickness of the bonding layer is 100 nm. Our result is very close to 50% of the total power reported by Intel when the thickness of the thin bonding layer is less than 5 nm. Therefore, our invariable coupling power technique is simpler than Intel＇s.     

Design and nonlinearity compensation of Fabry-Perot type tunable optical filters for dynamic strain sensing systems

The collected spectrum of the fiber Bragg grating （FBG） and the loss of the detected optical power are discussed with respect to the 3-dB bandwidth of a Fabry-Perot （F-P） type tunable optical filter （TOF）, respectively. And the optimized parameters of the TOF are obtained consequently. It is demonstrated that the relationship between the transmission wave- length of the TOF and its drive voltage is nonlinear. A new method to compensate the nonlinearity of the TOF is proposed. The linear sweeping of the transmission wavelength of the TOF is achieved through modifying the drive voltage using interpolation algorithm. It is observed that the average error and the maximum error of the transmission wavelength are reduced sharply under linear fit. The dynamic strain sensing is realized by use of a reference FBG and moving averaging algorithm in this system.     

避免MOS管在测试时受EOS损坏的方法

由于MOS管是浅结系列产品,极有可能在测试时遭到静电击穿或过压过流而损坏。文中主要介绍MOS管在测试过程中,会造成实际测试时器件加上了允许的最大电压、电流或功率而导致器件损坏的情况。例如,在测试过程中电源连接不良,测试片与器件接触不良,管脚接错,在测试程序中未设置正确的电压和电流钳位或DUT板损坏等。然后,针对此类现象的发生,提出了在测试过程中应采取的相应措施,从而有效地保证产品质量。     

一种改善LED背光亮度均匀性的新型反射膜研究

在LCD的LED背光腔体的底面设计了新型曲面形状及性能的反光膜,将扩散膜反射回灯腔底部的光重新反射回出光口以改善亮度均匀性能;在侧面设计了镜面反射膜,将位于LED矩阵边缘区域由LED射向灯腔侧壁的光反射重新射向出光口,增加了LED背光边缘区域的亮度,从而改善了背光边缘区域较暗的亮度不均匀状况.根据此类反射膜的设计完成了反射膜的制备,并应用于38 cm LED背光源样品.测试结果显示,设置反射膜的LED背光的亮度均匀性值为10.2%,明显优于未设置反射膜的值16.8%,亮度提高了29%左右,表明该种新型反射膜可以提高亮度并改善亮度均匀性.     

圆球微腔对水蒸汽的敏感特性仿真实验研究

研究了圆球微腔在水蒸汽传感中应用的可行性。通过测试在有/无水蒸汽的气室环境下,圆球微腔透射光谱的变化来对气室水蒸汽浓度情况进行传感测试。仿真实验结果显示:在有无水蒸汽干扰的条件下系统输出光强有明显的变化,即研制基于圆球微腔的传感器是可行的。     

位屏蔽多叉树搜索射频识别防碰撞算法

针对RFID树型防碰撞算法中时隙数多、数据通行量大等问题,提出了一种改进的多叉树防碰撞算法,阅读器准确检测碰撞位并向标签反馈碰撞位信息,标签对阅读器已知的ID位进行屏蔽,把ID号转换成连续碰撞的序列号.阅读器利用屏蔽位信息和标签返回的碰撞位编码信息,对标签进行分层分类搜索.通过对标签ID进行屏蔽,阅读器和标签间仅发送对方不知道的碰撞位信息.该算法减少了碰撞时隙和识别时隙,避免了空闲时隙,减少了阅读器和标签间的数据通信量.理论分析和仿真结果表明,该算法减少了系统的时隙总数和数据通信量,提高了阅读器的识别效率.     

Quantum theory analysis of the action micromechanism exerted on bioparticles from laser microbeams

The effect of laser microbeam trapping the bioparticles has been appfied widely in the biology .However the micromechanism of the acting that realizes the laser-microbeam trapping bioparticles is still lacking. In this paper ,the act microchenism of the gradiant force of laser microbeam for the bioparticles is analysed by means of quantum theory ,The result accords with our experiment.