In order to simplify the fabrication process,distribute the temperature uniformly and reduce the power consumption of the micro-hotplate（MHP） gas sensor,a planar-type gas sensor based on SnO2 thin film with suspende...In order to simplify the fabrication process,distribute the temperature uniformly and reduce the power consumption of the micro-hotplate（MHP） gas sensor,a planar-type gas sensor based on SnO2 thin film with suspended structure is designed through a MEMS process.Steady-state thermal analysis of the gas sensor and the closed membrane type sensor where the membrane overlaps the Si substrate is carried out with the finite element model,and it is shown that the suspended planar-type gas sensor has a more homogeneous temperature distribution and a lower power consumption.When the maximum temperature on the sensor reaches 383℃,the power consumption is only 7 mW,and the temperature gradient across the thin film is less than 14℃.To overcome the fragility of the suspended beams,a novel fabrication process in which the deposition of the gas sensing film occurs prior to the formation of suspended beams is proposed.The back side of the Si substrate is etched through deep reactive ion etching（DRIE） to avoid chemical pollution of the front side.The fabrication steps in which only four masks are used for the photolithography are described in detail.The Fe doped SnO2 thin film synthesized by sol-gel spin-coating is used as the gas sensing element.The device is tested on hydrogen and exhibits satisfactory sensing performance.The sensitivity increases with the rise of the concentration from 50×10-6 to 2000×10-6,and reaches about 30 at 2000×10-6.展开更多
To suppress the extension of the photo-sensitive area of a planar-type InGaAs detector, the structure of the detector was modified, and the small-diffusion-area diffusion method, circle-type covering contact and guard...To suppress the extension of the photo-sensitive area of a planar-type InGaAs detector, the structure of the detector was modified, and the small-diffusion-area diffusion method, circle-type covering contact and guard-ring were introduced. The laser-beam-induced-current （LBIC） technique was used to study the photo responsive characteristics of the photo-sensitive area of different detector structures. It was indicated that, by modifying the size of the diffusion area, the width of the circle-type covering contact, the distance between the guard-ring and the photo-sensitive area and the working status of the guard-ring, extension of the photo-sensitive area could be effectively suppressed, and the detector photo-sensitive area could be exactly defined.展开更多
对平面梯形结构多间隙谐振腔的模式分布、特性阻抗、耦合系数以及工作稳定性进行了研究.在此基础上给出了W波段高峰值功率扩展互作用速调管高频互作用系统设计,并采用三维粒子模拟(PIC)技术对电子的速度调制、群聚及其与高频场的相互作...对平面梯形结构多间隙谐振腔的模式分布、特性阻抗、耦合系数以及工作稳定性进行了研究.在此基础上给出了W波段高峰值功率扩展互作用速调管高频互作用系统设计,并采用三维粒子模拟(PIC)技术对电子的速度调制、群聚及其与高频场的相互作用和能量转换等物理过程进行了研究,定量给出了放大器的功率、带宽、效率以及增益等关键技术指标.PIC结果显示:在中心频率94.52 GHz以及电压16 k V、电流0.6 A的电子注参数下,最大输出功率达到1.8 k W,相应的增益和电子效率分别为47.7 d B和19.4%;扫频结果显示瞬时3 d B带宽为210 MHz.展开更多
基金The National Natural Science Foundation of China (No.58175122)the Natural Science Foundation of Jiangsu Province (No.BK2007185)+1 种基金the Natural Science Foundation of Higher Education Institutions of Jiangsu Province(No.07KJB460044)the Scientific Research Innovation Project for College Graduates in Jiangsu Province (No.CXZZ11_0340)
文摘In order to simplify the fabrication process,distribute the temperature uniformly and reduce the power consumption of the micro-hotplate（MHP） gas sensor,a planar-type gas sensor based on SnO2 thin film with suspended structure is designed through a MEMS process.Steady-state thermal analysis of the gas sensor and the closed membrane type sensor where the membrane overlaps the Si substrate is carried out with the finite element model,and it is shown that the suspended planar-type gas sensor has a more homogeneous temperature distribution and a lower power consumption.When the maximum temperature on the sensor reaches 383℃,the power consumption is only 7 mW,and the temperature gradient across the thin film is less than 14℃.To overcome the fragility of the suspended beams,a novel fabrication process in which the deposition of the gas sensing film occurs prior to the formation of suspended beams is proposed.The back side of the Si substrate is etched through deep reactive ion etching（DRIE） to avoid chemical pollution of the front side.The fabrication steps in which only four masks are used for the photolithography are described in detail.The Fe doped SnO2 thin film synthesized by sol-gel spin-coating is used as the gas sensing element.The device is tested on hydrogen and exhibits satisfactory sensing performance.The sensitivity increases with the rise of the concentration from 50×10-6 to 2000×10-6,and reaches about 30 at 2000×10-6.
基金supported by the Key Program ofthe National Natural Science Foundation of China(No.5063206)the Knowledge Innovation Program of the Chinese Academy of Sciences(Nos.C2-32,C2-50).
文摘To suppress the extension of the photo-sensitive area of a planar-type InGaAs detector, the structure of the detector was modified, and the small-diffusion-area diffusion method, circle-type covering contact and guard-ring were introduced. The laser-beam-induced-current （LBIC） technique was used to study the photo responsive characteristics of the photo-sensitive area of different detector structures. It was indicated that, by modifying the size of the diffusion area, the width of the circle-type covering contact, the distance between the guard-ring and the photo-sensitive area and the working status of the guard-ring, extension of the photo-sensitive area could be effectively suppressed, and the detector photo-sensitive area could be exactly defined.
文摘对平面梯形结构多间隙谐振腔的模式分布、特性阻抗、耦合系数以及工作稳定性进行了研究.在此基础上给出了W波段高峰值功率扩展互作用速调管高频互作用系统设计,并采用三维粒子模拟(PIC)技术对电子的速度调制、群聚及其与高频场的相互作用和能量转换等物理过程进行了研究,定量给出了放大器的功率、带宽、效率以及增益等关键技术指标.PIC结果显示:在中心频率94.52 GHz以及电压16 k V、电流0.6 A的电子注参数下,最大输出功率达到1.8 k W,相应的增益和电子效率分别为47.7 d B和19.4%;扫频结果显示瞬时3 d B带宽为210 MHz.
