Jingquan Tian

Preparation and performance of silicon microchannel plate

A silicon microchannel plate (Si-MCP), with 15-25 aspect ratio of the microchannel, 6-20 microns diameter and 6-8 microns space, was prepared by Inductively Coupled Plasma (ICP) and LPCVD. The inner surface topography of microchannel was surveyed, the bulk resistance 7.3 mega ohm and electron gain 110 of MCP were tested by ultraviolet optoelectronic method. The plasma-etching lag in processing the microchannel array was analyzed and discussed. Finally, we compared the electron gain of silicon microchannel plate with traditional glass one. Our work proved the feasibility of making Si-MCP by microfabrication and semiconductor process.

X-Ray Intensifier with the Transmission Type CsI/MCP Cathode and Lixiscope of Real-Time Imaging System

In this paper, the fabrication method and structure of the integral type CsI/MCP X-ray cathode in intensifiers was introduced, the transmission type CsI/MCP X-ray cathode of practical application in intensifier was indicated especially. The response characteristic,the quantum efficiency and noise characteristic of CsI/MCP X-ray cathode in intensifier was given and analysed, respectively. A new Lixiscope of real-time imaging system composed of Lixiscope, the image collection and procession system of CCD) was studied by experimental method. The optimized resolution 6.3lp/mm of imaging was obtained which achieving the anticipated goals to decrease the flashing noise and ensure the brightness of the image. Using this system, the finger and the wrist joint of human body can be diagnosed and detected. The corresponding photographs were given which indicating a potential applications of this new type of low-intensity x-ray real-time imaging system in biomedicine and non-destructive dections.

Technological improvements on the image quality in the low-intensity x-ray real-time imaging system

In this paper, the noise and optical aberration which were two controllable factors that affect the image quality in the single-proximity-focusing x-ray image-intensifier were studied. By decreasing the electron gain of microchannel plate (MCP), the noise of the x-ray image-intensifier can be decreased. The optimal operating condition for the image intensifier and the CCD were also investigated. Based on this investigation, the flash-noise of the x-ray image-intensifier can be decreased and the brightness of the image can be improved. At the end of the paper, some results on the image-capturing of the cool CCD with low noise were presented.

Study of microsphere plate photomultiplier tube

The photomultiplier tube (PMT) that can work in different wavelength is an important detector device in remote sense technology. Microsphere plate using glass beads 50to 70μm in diameter sintered together is the core component of the microsphere plate photomultiplier tube It is a novel two-dimension electron multiplier. The electrons gain for a single plate is about 1017 and do not have the phenomenon of ion-feedback. Furthermore the fabrication process is very easy. In this paper, much interest was put on the microsphere plate photomultiplier tube. Based on the analyses from the theory and the experiment result, we point out the key technology for fabricating PMT is how to obtain glass beads with narrow range in diameter and how to sinter the glass beads with a sufficient pylome. Factors affect the gradating technology and sintering process along with the solution to them is presented. In the last, the structure scheme and technological characteristic for fabricating microsphere plate photomultiplier tube were given. The pulse rising-time of MSP-PMT is below 400ps suitable to the detection of high-speed pulse. As easy to be fabricated and has great advantage over MCP multiplier in the ratio of performance to price, the microsphere plate photomultiplier tube is a promising dim-light detector.

New MCP reflection x-ray-sensitive film of variable-density halide

Microchannel plate (MCP) is a device of two-dimension array electron multiplier. The detection ability to 40 - 60 KeV X-ray for MCP was increased by coating the halide such as CsI, CsBr and KBr on input plate of MCP, that forming a reflection X-ray sensitive film in the channel with depth of 2 - 3 times of diameter below the input plate. Experiment results show that the output response of MCP with variable density structure CsI to X-ray is about 5 - 6 times higher than that with constant density structure, and of one order of magnitude stronger than that without coating the film. Comparatively, the output response of MCP with CsI sensing film is best, CsBr medium and KBr bad. The response characteristics of MCP with CsI to X-ray related to film materials, structure, component distribution and process. Several experiment curves denoted the response characteristics to X-ray at different target voltage and current. The results basically accorded with the theory about quantum detection efficiency of reflection X-ray cathode. This new MCP reflection X-ray sensitive film of variable density halide has been successfully applied in X-ray imaging detecting devices. The corresponding detection system will find widely and potential applications in the field of medical diagnosis, nondestructive evaluation and security inspection, etc.

New way of preparing ion barrier ultrathin film without pollution

A new technology and method preparing ions barrier film on the input face of multi-hole substratum, MCP, without carbon pollution were studied and introduced in this paper. The composition of the film and the performance of MCP coated with ion barrier film were tested by XPS and UV photoelectric emission method. The new process made the carbon content largely decrease in the film, and the characteristics of MCP unmodified.

New structure x-ray cathode for x-ray intensifier of single proximity focus

This paper introduces a new structure X-ray cathode consisting of new structure haloid coating integrated on the input surface of MCP that is applied in single proximity x-ray intensifier. The current response characteristics of different structure CsI, CsBr and KBr cathodes are compared. The conclusion of excellent output response of the dense-loose-dense three-layer new structure CsI Cathode in the energy range 40 - 50 Kev is obtained.

Performance of Microchannel Plates with Al2O3 Ion Barrier Film after High-Temperature Degassing

The ion barrier film of microchannel plate (MCP) plays a most important role in the third generation low-light level image intensifier to prevent the feedback of positive ions, protect the photocathode and prolong the operating life of image intensifier. In this paper, the influence of high-temperature degassing on the performances of the ion barrier film and the MCP itself were investigated by the experiments. The high-temperature degassing and the corresponding measurement system of MCP were shown, the detailed technology process was given, and the changes of the ion barrier films morphology and the MCPs electrical performance after high-temperature degassing were compared. For a MCP with an ion barrier film, it was found that the electron gain decreased, the bulk resistance increased, the grain size of the ion barrier film increased and the dead-voltage decreased after high-temperature degassing.

ZnO-based material and UV detector

ZnO is the most promising material for the application of an ultraviolet (UV) detector. However the shortage of ptype ZnO becomes the biggest blockage for fabricating ZnO-based semiconductor device. In this paper, following experiments had been done: Firstly, the zinc nitride powders were synthesized through the nitridation reaction of Zn power with NH3, and the optimized synthesis temperature was at 600°C. Next, the zinc nitride powder was fabricated into a zinc nitride sputtering target by a single pressing process. Thirdly a thin layer of zinc nitride film was formed on silicon and quartz substrate using magnetron sputtering method. Fourthly, the zinc nitride film was oxidized into p-type ZnO, and the best optimized temperature for forming p-type ZnO by oxidizing Zn3N2 thin film was at 500°C. Lastly, the ohmic contact for p-ZnO and ZnO based detector were fabricated. It was found Al and Ni/Au showed ohmic contact properties to n- Si and p-ZnO, respectively, and the p-ZnO/n-Si junction as a UV detector was feasible.

Investigations on ion transmission characteristics of the ion barrier films in Generation III image tubes

The stopping power of ion barrier films (IBFs) of Microchannel Plate (MCP) in Generation III image tubes for incident positive ions was described in this paper. Nuclear Stopping Power, Electronic Stopping Power and Mean Range were introduced. These concepts were analyzed and discussed, combined with Tomas-Fermi shielding potential. The results of a Monte Carlo simulation on Nuclear Stopping Power, Electronic Stopping Power and Mean Range were also presented when the ions with different energies were perpendicularly incident to Al2O3 and SiO2 films. The results indicate that the stopping power of Al2O3 film is stronger than that of SiO2, and the selection of Al2O3 is reasonable and feasible.