循环间歇溅射工艺对PLT薄膜性能的影响

采用射频磁控溅射技术利用循环间歇溅射工艺,在Pt/Ti/SiO2/Si基片上制备出了镧钛酸铅(PLT)薄膜。通过原子力显微镜、X-射线衍射仪分析了循环间歇溅射工艺对薄膜形貌、结构和铁电性能的影响。实验结果表明,相比于连续溅射工艺,循环间歇溅射工艺的基片温度较低,且制得的PLT薄膜晶粒细小、均匀,结构致密。薄膜具有纯钙钛矿型结构,循环次数从1次增加到3次,其(100)和(200)峰衍射强度逐渐增强,结晶性提高,铁电性能逐渐增强,其饱和极化强度由28μC/cm2增大到53μC/cm2,剩余极化强度由5μC/cm2增大到12μC/cm2。循环4次溅射后,薄膜的结晶性和铁电性开始下降。     

360-nm Photoluminescence from Silicon Oxide Films Embedded with Silicon Nanocrystals

Si-rich silicon oxide films were deposited by RF magnetron sputtering onto composite Si/SiO2 targets. After annealed at different temperature, the silicon oxide films embedded with silicon nanocrystals were obtained. The photoluminescenee（PL） from the silicon oxide films embedded with silicon nanocrystals was observed at room temperature. The strong peak is at 360 nm, its position is independent of the annealing temperature. The origin of the 360-nm PL in the silicon oxide films embedded with silicon nanoerystals was discussed.     

高频RFID读写器射频模拟前端的实现

射频识别(RFID)系统主要由RFID读写器和RFID电子标签两部分组成.给出了高频(13.56MHz)RFID系统中读写器射频模拟前端的电路设计,符合ISO/IEC14443 type A/type B,ISO/IEC15693和ISO/IEC18000-3中任一个标准的读写器芯片设计均可采用,设计工艺采用了中芯国际0.35μm 2P3M混合CMOS技术,并给出了Cadence环境下的仿真结果.     

ZnO单晶薄膜光电响应特性

对采用MOCVD方法沉积的ZnO单晶薄膜的欧姆接触特性、光电特性进行了研究,并对比研究了射频溅射沉积SiO2抗反射膜对ZnO薄膜I-V、光电特性的影响.实验结果表明,非合金Al/ZnO金属体系与n型ZnO形成了良好的欧姆接触,溅射沉积SiO2在ZnO表面引入了载流子陷阱,影响I-V特性,延长了光响应下降时间.ZnO单晶薄膜光电导也具有时间退化现象.     

0.35 μm CMOS T/R Switch for 2.4 GHz Short Range Wireless Applications

This paper describes the design and implementation of a transmit/receive switch for 2.4 GHz ISM band applications. The T/R switch is implemented in a 0.35 m bulk CMOS process and it occupies 150 m · 170 m of die area. A parasitic MOSFET model including bulk resistance is used to optimize the physical dimensions of the transistors with regard to insertion loss and isolation. The measured insertion loss is 1.3 dB without port matching. Simulations using measured s-parameters indicate that an insertion loss of 0.8 dB can be obtained with a conjugate match. The measured isolation is 42 dB and the maximum transmit power is 16 dBm.     

An open volume, high isolation, radio frequency surface coil system for pulsed magnetic resonance

We present an open volume, high isolation, RF system suitable for pulsed NMR and EPR spectrometers with reduced dead time. It comprises a set of three RF surface coils disposed with mutually parallel RF fields and a double-channel receiver (RX). Theoretical and experimental results obtained with a prototype operating at about 100 MHz are reported. Each surface RF coil (diameter 5.5 cm) was tuned to f₀ = 100.00 ± 0.01 MHz when isolated. Because of the mutual coupling and the geometry of the RF coils, only two resonances at f₁ = 97.94 MHz and f₂ = 101.85 MHz were observed. We show they are associated with two different RF field spatial distributions. In continuous mode (CW) operation the isolation between the TX coil and one of the RX coils (single-channel) was about −10 dB. By setting the double-channel RF assembly in subtraction mode the isolation values at f₁ or f₂ could be optimised to about −75 dB. Following a TX RF pulse (5 μs duration) an exponential decay with time constant of about 600 ns was observed. The isolation with single-channel RX coil was about −11 dB and it increased to about −47 dB with the double-channel RX in subtraction mode. Similar results were obtained with the RF pulse frequency selected to f₂ and also with shorter (500 ns) RF pulses. The above geometrical parameters and operating frequency of the RF assembly were selected as a model for potential applications in solid state NMR and in free radical EPR spectroscopy and imaging.     

储存环高频剔除系统

 介绍了用于电子储存环部分填充和非均匀填充的一种实验装置,它利用储存环中电子运动所具有的横向自由振荡和束团脉冲的时间结构这一特性,采用外加激励的方法使其产生共振,从而使得储存环中部分束团中的电子丢失,形成储存环的部分填充和非均匀填充。还扼要介绍了用高频剔除系统在储存环上实现不同填充方式时的束流积累结果。     

Nonlinear phase adjustment of selective excitation pulses

A continuous transformation of an RF waveform with a modified Korteweg-de Vries equation or generalization can be used to adjust the phase behavior of a selective excitation pulse while preserving the magnitude behavior of the spin response. This transformation has applications in removing or adding to the nonlinear phase properties of a selected region.     

C波段pHEMT单片Gilbert混频器

采用0.5μmpHEMT工艺研制了Gilbert式单片混频器,设计采用了电流注入技术及跨导级源端负反馈技术,在C波段测试表明:变频增益大于1.5dB,单边带噪声系数典型值为12.5dB,变频带宽约为DC～1GHz,所需本振功率实测值为1.6dBm。