In this paper, a new pre-alignment approach based on Four-Quadrant-Photo-Detector （FQPD） for IC mask is presented. The voltage outputs from FQPDs are the functions of alignment mark＇s position offsets with respect ...In this paper, a new pre-alignment approach based on Four-Quadrant-Photo-Detector （FQPD） for IC mask is presented. The voltage outputs from FQPDs are the functions of alignment mark＇s position offsets with respect to FQPDs. The functions are obtained with least squares error （LSE）-based polynomial fitting after the normalization of experimental data. As the acquired functions are not monotonic about their variables, the alignment mark＇s position offset cannot be given by direct inverse operation on the obtained functions. However, the piecewise polynomial fitting gives the inverse function, with which the alignment mark＇s position offset can be predicted according to the voltage outputs of FQPDs. On the basis of prediction, a pre-alignment control strategy is proposed. The feasibility and robustness of the pre-alignment approach is shown by experiments. Furthermore, the results demonstrate that the maximum error of mask＇s position offset in the X- and Y- directions is less than 15μm after coarse pre-alignment. Keywords： Four-Quadrant-Photo-Detector （FQPD）, pre-alignment, IC mask, polynomial fitting展开更多
We conducted a theoretical study on the electronic properties of a single-layer graphene asymmetric quantum well.Quantification of energy levels is limited by electron–hole conversion at the barrier interfaces and fr...We conducted a theoretical study on the electronic properties of a single-layer graphene asymmetric quantum well.Quantification of energy levels is limited by electron–hole conversion at the barrier interfaces and free-electron continuum.Electron–hole conversion at the barrier interfaces can be controlled by introducing an asymmetry between barriers and taking into account the effect of the interactions of the graphene sheet with the substrate.The interaction with the substrate induces an effective mass to carriers,allowing observation of Fabry–P′erot resonances under normal incidence and extinction of Klein tunneling.The asymmetry,between barriers creates a transmission gap between confined states and free-electron continuum,allowing the large graphene asymmetric quantum well to be exploited as a photo-detector operating at mid-and far-infrared frequency regimes.展开更多
A new type of ultraviolet photo-detectors (UVPDs) based on a bundle of highly aligned SiC nanowires was fabricated and the photo-electric properties of the UVPDs including I-V characteristics and time response were st...A new type of ultraviolet photo-detectors (UVPDs) based on a bundle of highly aligned SiC nanowires was fabricated and the photo-electric properties of the UVPDs including I-V characteristics and time response were studied in this work. SiC nanowires were prepared by pyrolysis of a polymer precursor with ferrocene as the catalyst by a CVD route. The diameters of SiC nanowires varied from 100 to 200 nm while they were some centimeters long and the SiC nanowires were with zinc blended cubic form ( -SiC) tested by X-ray diffraction. A bundle of nanowires was fixed onto two legs' base by conductive silver paste to form the UVPDs. The electrical measurement of the device showed a significant increase of current when the device was exposed to 254 nm UV light, and the rising time of the device is very short, but the falling time is relatively long. Our results show that the UVPDs based on SiC nanowires have excellent electrical and optical properties which can be potentially applied.展开更多
采用光离子化检测器(PID)传感器对挥发性有机化合物(VOC)气体进行检测,通过对PID的研究,自行设计适合本系统的PID检测器结构,并搭建了一套完整的检测系统。通过实验证明:所搭建的以PID检测器为核心的VOC气体检测系统已能够实现对VOC气...采用光离子化检测器(PID)传感器对挥发性有机化合物(VOC)气体进行检测,通过对PID的研究,自行设计适合本系统的PID检测器结构,并搭建了一套完整的检测系统。通过实验证明:所搭建的以PID检测器为核心的VOC气体检测系统已能够实现对VOC气体的定量检测。确定实验流量为160~170 m L/min,且在(0~5)×10-6内传感器响应呈线性关系。展开更多
基金This work was supported by National High Technology Research and Development Program of PRC (No. 2002AA420040)National 973 Program of PRC (No. 2002CB312200).
文摘In this paper, a new pre-alignment approach based on Four-Quadrant-Photo-Detector （FQPD） for IC mask is presented. The voltage outputs from FQPDs are the functions of alignment mark＇s position offsets with respect to FQPDs. The functions are obtained with least squares error （LSE）-based polynomial fitting after the normalization of experimental data. As the acquired functions are not monotonic about their variables, the alignment mark＇s position offset cannot be given by direct inverse operation on the obtained functions. However, the piecewise polynomial fitting gives the inverse function, with which the alignment mark＇s position offset can be predicted according to the voltage outputs of FQPDs. On the basis of prediction, a pre-alignment control strategy is proposed. The feasibility and robustness of the pre-alignment approach is shown by experiments. Furthermore, the results demonstrate that the maximum error of mask＇s position offset in the X- and Y- directions is less than 15μm after coarse pre-alignment. Keywords： Four-Quadrant-Photo-Detector （FQPD）, pre-alignment, IC mask, polynomial fitting
文摘We conducted a theoretical study on the electronic properties of a single-layer graphene asymmetric quantum well.Quantification of energy levels is limited by electron–hole conversion at the barrier interfaces and free-electron continuum.Electron–hole conversion at the barrier interfaces can be controlled by introducing an asymmetry between barriers and taking into account the effect of the interactions of the graphene sheet with the substrate.The interaction with the substrate induces an effective mass to carriers,allowing observation of Fabry–P′erot resonances under normal incidence and extinction of Klein tunneling.The asymmetry,between barriers creates a transmission gap between confined states and free-electron continuum,allowing the large graphene asymmetric quantum well to be exploited as a photo-detector operating at mid-and far-infrared frequency regimes.
基金the National Natural Science Foundation of China (Grant No. 11104348)the School Pre-research of National University of Defense Technology (Grant No. JC11-02-08) for the financial support to this work
文摘A new type of ultraviolet photo-detectors (UVPDs) based on a bundle of highly aligned SiC nanowires was fabricated and the photo-electric properties of the UVPDs including I-V characteristics and time response were studied in this work. SiC nanowires were prepared by pyrolysis of a polymer precursor with ferrocene as the catalyst by a CVD route. The diameters of SiC nanowires varied from 100 to 200 nm while they were some centimeters long and the SiC nanowires were with zinc blended cubic form ( -SiC) tested by X-ray diffraction. A bundle of nanowires was fixed onto two legs' base by conductive silver paste to form the UVPDs. The electrical measurement of the device showed a significant increase of current when the device was exposed to 254 nm UV light, and the rising time of the device is very short, but the falling time is relatively long. Our results show that the UVPDs based on SiC nanowires have excellent electrical and optical properties which can be potentially applied.
文摘采用光离子化检测器(PID)传感器对挥发性有机化合物(VOC)气体进行检测,通过对PID的研究,自行设计适合本系统的PID检测器结构,并搭建了一套完整的检测系统。通过实验证明:所搭建的以PID检测器为核心的VOC气体检测系统已能够实现对VOC气体的定量检测。确定实验流量为160~170 m L/min,且在(0~5)×10-6内传感器响应呈线性关系。
