基于纳米多晶硅薄膜晶体管磁传感器制作工艺和特性

A magnetic field sensor based on nano-polysilicon thin films transistors（TFTs） with Hall probes is proposed.The magnetic field sensors are fabricated on <100> orientation high resistivity（ρ>500Ω·cm） silicon substrates by using CMOS technology,which adopt nano-polysilicon thin films with thicknesses of 90 nm and heterojunction interfaces between the nano-polysilicon thin films and the high resistivity silicon substrates as the sensing layers.The experimental results show that when V_DS = 5.0 V,the magnetic sensitivities of magnetic field sensors based on nano-polysilicon TFTs with length-width ratios of 160μm/80μm,320μm/80μm and 480μm/80μm are 78 mV/T,55 mV/T and 34 mV/T,respectively.Under the same conditions,the magnetic sensitivity of the obtained magnetic field sensor is significantly improved in comparison with a Hall magnetic field sensor adopting silicon as the sensing layers.     

应力和电阻率可控的适用于高品质因子MEMS器件的原位掺硼LPCVD多晶硅薄膜

The simultaneous control of residual stress and resistivity of polysilicon thin films by adjusting the deposition parameters and annealing conditions is studied. In situ boron doped polysilicon thin films deposited at 520 ℃ by low pressure chemical vapor deposition （LPCVD） are amorphous with relatively large compressive residual stress and high resistivity. Annealing the amorphous films in a temperature range of 600-800 ℃ gives polysilicon films nearly zero-stress and relatively low resistivity. The low residual stress and low resistivity make the polysilicon films attractive for potential applications in micro-electro-mechanical-systems （MEMS） devices, especially in high resonance frequency （high-f） and high quality factor （high-Q） MEMS resonators. In addition, polysilicon thin films deposited at 570 ℃ and those without the post annealing process have low resistivities of 2-5 mΩ·cm. These reported approaches avoid the high temperature annealing process （〉 1000 ℃）, and the promising properties of these films make them suitable for high-Q and high-f MEMS devices.     

A VHF PECVD Micro-Crystalline Silicon Bottom Gate TFT with a Thin Incubation Layer

The incubation layer with amorphous structure between the substrate and crystalline layer may obviously affect the performance for a microcrystalline Si thin film transistor (μc-Si TFT),especially for the bottom gate TFT(BGTFT).It is found that decreasing the ratio of SiH4/（H2+SiH4） is an effective way to decrease the incubation layer thickness of μc-Si directly deposited by VHF PECVD without any further thermal or laser treatment.Based on the μc-Si with a thin incubation layer,the BG-TFT with Al/SiNx/μc-Si/n+μc-Si/Al structure is fabricated.The ratio of on-state current to off-state current is up to 10.6,the mobility is around 0.7cm2/（V·s）,and the threshold voltage is about 5V.     

纳米硅/单晶硅异质结MAGFET制作及特性

A MAGFET using an nc-Si/c-Si heterojunction as source and drain was fabricated by CMOS technology, using two ohm-contact electrodes as Hall outputs on double sides of the channel situated 0.7L from the source. The experimental results show that when VDS = -7.0 V, the magnetic sensitivity of the single nc-Si/c-Si heterojunction magnetic metal oxide semiconductor field effect transistor （MAGFET） with an L ： W ratio of 2 ： 1 is 21.26 mV/T, and that with an L ： W ratio of 4 ： 1 is 13.88 mV/T. When the outputs of double nc-Si/c-Si heterojunction MAGFETs with an L ： W ratio of 4 ： 1 are in series, their magnetic sensitivity is 22.74 mV/T, which is an improvement of about 64% compared with that of a single nc-Si/c-Si heterojunction MAGFET.     

衬底温度对In掺杂CdO薄膜的结构和性能的影响

Transparent indium-doped cadmium oxide（In-CdO） thin films were deposited on quartz glass substrates by pulsed laser deposition（PLD） from an ablating Cd-In metallic target.The effect of substrate temperature on the structural,optical and electrical properties of In-doped CdO thin films were studied in detail.The optical transmittance of In doped CdO films are obviously influenced by the substrate temperature.All films exhibit a transmittance higher than 75%in the visible region.More significantly,In-doping leads to an evident widening of optical band gap from 2.56 to 2.91 eV;and the increase in optical band gap is found to depend on the deposition temperature.It is also seen that the electrical properties of these films strongly depend on the substrate temperature. The In-CdO thin film grown at 300℃has low resistivity(1.15×10^-4Ω·cm),high carrier concentration(5.35×10²⁰ cm^-3),and high mobility（101.43 cm²/（V·s））.     

TiO2 Thin Film UV Detectors Deposited by DC Reactive Magnetron Sputtering

CrystallineTiO2 thin films were prepared by DC reactive magnetron sputtering on indium--tin oxide(ITO) thin film deposited on quartz substrate, the photoconductive UV detector on TiO2 thin films was based on a sandwich structure of C/TiOz/ITO. The measurement of the I—V characteristics for these devices shows good ohmic contact. The photoresponse of TiO2 thin films was analyzed at different bias voltage. The detector shows a good photoresponse with a rise time of 2 s and a fall time of 40 s, the photocurrent is linearly increased with the bias voltage.     

CPW Circulators with Barium Ferrite Thin Films

A miniaturized circulator using barium ferrite films with a coplanar waveguide(CPW) structure is designed and optimized by high frequency electromagnetic field simulations based on finite element methods.The best circulation performance of the film circulator based on 10 μm thick barium ferrite thin films is obtained with an insertion loss of 0.13 dB and an isolation of 22.89 dB around 36.9 GHz.The microwave characteristics of film circulators with CPW and CPW with ground(CPWG) structures have been compared.The influences of the gap between the ground and the signal line,and the ferromagnetic resonance line width on the microwave properties are also studied.     

Effect of thickness on optoelectrical properties of Nb-doped indium tin oxide thin films deposited by RF magnetron sputtering

Niobium-doped indium tin oxide （ITO:Nb） thin films are prepared on glass substrates with various film thicknesses by radio frequency （RF） magnetron sputtering from one piece of ceramic target material. The effects of thickness （60-360 nm） on the structural, electrical and optical properties of ITO: Nb films are investigated by means of X-ray diffraction （XRD）, ultraviolet （UV）-visible spectroscopy, and electrical measurements. XRD patterns show the highly oriented （400） direction. The lowest resistivity of the films without any heat treatment is 3.1×10^-4 Ω·cm^-1, and the resistivity decreases with the increase of substrate temperature. The highest Hall mobility and carrier concentration are 17.6 N·S and 1.36×10²¹ cm^-3, respectively. Band gap energy of the films depends on substrate temperature, which varies from 3.48 eV to 3.62 eV.     

Nano-ZnO film preparation at low temperature and the optical indices calculation

The refractive indices of thin films based on Kramers-Kronig theory are corrected. And the correction theory is used to determine the optical indices of nano-ZnO thin films prepared by low temperature sol-gel method. The calculated results indicate that in the visible （Vis） range, the refractive indices of nano-ZnO thin films exhibit a slight abnormal dispersion, while in the ultraviolet （UV） region, the refractive indices increase with wavelengths increasing （normal dispersion）. But the refractive indices show complex change near the absorption edge. The maximum refractive index （1.95） of nano-ZnO thin films within UV range at low temperature annealing is much lower than that of the films annealed at high temperature. The absorption and refractive indices are closely related to the defects in nano-ZnO thin films.     

RF功率对非晶铟镓锌氧薄膜和器件电学特性的影响

The influence of radio frequency(RF) power on the properties of magnetron sputtered amorphous indium gallium zinc oxide(a-IGZO) thin films and the related thin-film transistor(TFT) devices is investigated comprehensively.A series of a-IGZO thin films prepared with magnetron sputtering at various RF powers are examined.The results prove that the deposition rate sensitively depends on RF power.In addition,the carrier concentration increases from 0.91 x 1019 to 2.15 x 1019 cm-3 with the RF power rising from 40 to 80 W,which may account for the corresponding decrease in the resistivity of the a-IGZO thin films.No evident impacts of RF power are observed on the surface roughness,crystalline nature and stoichiometry of the a-IGZO samples.On the other hand,optical transmittance is apparently influenced by RF power where the extracted optical band-gap value increases from 3.48 to 3.56 eV with RF power varying from 40 to 80 W,as is supposed to result from the carrierinduced band-filling effect.The rise in RF power can also affect the performance of a-IGZO TFTs,in particular by increasing the field-effect mobility clearly,which is assumed to be due to the alteration of the extended states in a-IGZO thin films.     

铟掺杂显著改善硫化锌薄膜光电性能研究

Abstract： This paper reports a new material, indium-doped ZnS （ZnS：In） film, which is fabricated for the first time to improve its electrical and optical performance. By electron beam evaporation technology and the optimized annealing treatment, high quality ZnS：In film is prepared. XRD indicates that the incorporation of 6 at.% indium atoms into ZnS film causes little lattice deformation. The AFM results imply that large sized particles are compactly dispersed in the ZnS：In layer and results in an unsmooth surface. Electrical and optical property tests show that the resistivity of ZnS film is greatly decreased to 4.46×10-2 Ω.cm and the optical transmittance is improved to 85% in the visible region. Comparing with the results in other literatures, significant progress in electrical/optical performance has been made in this paper.     

厚度对柔性衬底上制备的ZnO:Zr透明导电薄膜性能的影响

Transparent conducting zirconium-doped zinc oxide （ZnO：Zr） thin films with high transparency, low resistivity and good adhesion were successfully prepared on water-cooled flexible substrates （polyethylene glycol terephthalate, PET） by RF magnetron sputtering. The structural, electrical and optical properties of the films were studied for different thicknesses in detail. X-ray diffraction （XRD） and scanning electron microscopy （SEM） revealed that all the deposited films are polycrystalline with a hexagonal structure and a preferred orientation perpendicular to the substrate. The lowest resistivity achieved is 1.55 × 10-3 Ω·cm for a thickness of 189 nm with a Hall mobility of 17.6 cm2/（V·s） and a carrier concentration of 2.15×1020 cm-3. All the films present a high transmittance of above 90% in the wavelength range of the visible spectrum.     

有源层溅射温度对非晶铟镓锌氧薄膜晶体管电学特性的影响

The effect of active layer deposition temperature on the electrical performance of amorphous InGaZnO （a-IGZO） thin film transistors （TFTs） is investigated. With increasing annealing temperature, TFT performance is firstly improved and then degraded generally. Here TFTs with best performance defined as ＂optimized-annealed＂ are selected to study the effect of active layer deposition temperature. The field effect mobility reaches maximum at deposition temperature of 150℃ while the room-temperature fabricated device shows the best subthreshold swing and off-current. From Hall measurement results, the carrier concentration is much higher for intentional heated a-IGZO films, which may account for the high off-current in the corresponding TFT devices. XPS characterization results also reveal that deposition temperature affects the atomic ratio and Ols spectra apparently. Importantly, the variation of field effect mobility of a-IGZO TFTs with deposition temperature does not coincide with the tendencies in Hall mobility of a-IGZO thin films, Based on the further analysis of the experimental results on a-IGZO thin films and the corresponding TFT devices, the trap states at front channel interface rather than IGZO bulk layer properties may be mainly responsible for the variations of field effect mobility and subthreshold swing with IGZO deposition temperature.     

Software Radio——Software Radio： A Review of Design Considerations and Digital Hardware Choices

This paper reviews the requirements for Software Defined Radio （SDR） systems for high-speed wireless applications and compares how well the different technology choices available- from ASICs, FPGAs to digital signal processors （DSPs） and general purpose processors （GPPs） - meet them.     

EEFA： Energy Efficiency Frame Aggregation Scheduling Algorithm for IEEE 802.11n Wireless Network

Packet size is restricted due to the error-prone wireless channel which drops the network energy utilization. Furthermore, the frequent packet retransmissions also lead to energy waste. In order to improve the energy efficiency of wireless networks and save the energy of wireless devices, EEFA （Energy Efficiency Frame Aggregation）, a frame aggregation based energy-efficient scheduling algorithm for IEEE 802.11n wireless network, is proposed. EEFA changes the size of aggregated frame dynamically according to the frame error rate, so as to ensure the data transmission and retransmissions completed during the TXOP and reduce energy consumption of channel contention. NS2 simulation results show that EEFA algorithm achieves better performance than the original frame-aggregation algorithm.     

基于代数签名且支持数据动态更新的云数据完整性验证方案(英文)

Cloud storage is one of the main application of the cloud computing. With the data services in the cloud, users is able to outsource their data to the cloud, access and share their outsourced data from the cloud server anywhere and anytime. However, this new paradigm of data outsourcing services also introduces new security challenges, among which is how to ensure the integrity of the outsourced data. Although the cloud storage providers commit a reliable and secure environment to users, the integrity of data can still be damaged owing to the carelessness of humans and failures of hardwares/softwares or the attacks from external adversaries. Therefore, it is of great importance for users to audit the integrity of their data outsourced to the cloud. In this paper, we first design an auditing framework for cloud storage and proposed an algebraic signature based remote data possession checking protocol, which allows a third-party to auditing the integrity of the outsourced data on behalf of the users and supports unlimited number of verifications. Then we extends our auditing protocol to support data dynamic operations, including data update, data insertion and data deletion. The analysis and experiment results demonstrate that our proposed schemes are secure and efficient.     

SDN-Based Data Offioading for 5G Mobile Networks

The rapid growth of 3G/4G enabled devices such as smartphones and tablets in large numbers has created increased demand formobile data services.Wi-Fi offloading helps satisfy the requirements of data-rich applications and terminals with improved multi-media.Wi-Fi is an essential approach to alleviating mobile data traffic load on a cellular network because it provides extra capaci-ty and improves overall performance.In this paper,we propose an integrated LTE/Wi-Fi architecture with software-defined net-working(SDN)abstraction in mobile backhaul and enhanced components that facilitate the move towards next-generation 5G mo-bile networks.Our proposed architecture enables programmable offloading policies that take into account real-time network condi-tions as well as the status of devices and applications.This mechanism improves overall network performance by deriving real-time policies and steering traffic between cellular and Wi-Fi networks more efficiently.     

A Trusted Measurement Scheme Suitable for the Clients in the Trusted Network

The trusted network connection is a hot spot in trusted computing field and the trust measurement and access control technology are used to deal with network security threats in trusted network. But the trusted network connection lacks fine-grained states and real-time measurement support for the client and the authentication mechanism is difficult to apply in the trusted network connection, it is easy to cause the loss of identity privacy. In order to solve the above- described problems, this paper presents a trust measurement scheme suitable for clients in the trusted network, the scheme integrates the following attributes such as authentication mechanism, state measurement, and real-time state measurement and so on, and based on the authentication mechanism and the initial state measurement, the scheme uses the real- time state measurement as the core method to complete the trust measurement for the client. This scheme presented in this paper supports both static and dynamic measurements. Overall, the characteristics of this scheme such as fine granularity, dynamic, real-time state measurement make it possible to make more fine-grained security policy and therefore it overcomes inadequacies existing in the current trusted network connection.