Qingduo Duanmu

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.

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.

Electrolyte diffusion model in macroporous silicon photo-electrochemical etching and its application in macropore diameter control

In photo-electrochemical etching for macroporous silicon, the electrolyte diffusion in the macropore greatly influences the formation of macroporous silicon, especially the etching rate and macropore diameter. In this study, the electrolyte diffusion was investigated systematically. We focused on the establishment of the electrolyte diffusion model and its impact on the etching rate and macropore diameter. By solving the diffusion equation, the electrolyte diffusion model was deduced, which is different from the commonly accepted model. The main difference is that, in the model, the HF concentration at the macropore tip decreases nonlinearly with macropore length. The module can effectively predict the etching rate. Based on this model, the practical method of etching current density adjustment for fabricating high aspect ratio macroporous silicon was proposed. In addition, the samples were fabricated with a constant etching current density and corrected etching current density. The experimental result indicates that the novel electrolyte diffusion model is practical. The finding from this study shows that the adjustment of etching current density based on the electrolyte diffusion model can effectively control the macropore diameter of high aspect ratio macroporous silicon.In photo-electrochemical etching for macroporous silicon, the electrolyte diffusion in the macropore greatly influences the formation of macroporous silicon, especially the etching rate and macropore diameter. In this study, the electrolyte diffusion was investigated systematically. We focused on the establishment of the electrolyte diffusion model and its impact on the etching rate and macropore diameter. By solving the diffusion equation, the electrolyte diffusion model was deduced, which is different from the commonly accepted model. The main difference is that, in the model, the HF concentration at the macropore tip decreases nonlinearly with macropore length. The module can effectively predict the etching rate. Based on this model, the practical method of etching current density adjustment for fabricating high aspect ratio macroporous silicon was proposed. In addition, the samples were fabricated with a constant etching current density and corrected etching current density. The experimental result in...

Silicon macroporous arrays with high aspect ratio prepared by ICP etching

This paper reports on a macroporous silicon arrays with high aspect ratio, the pores of which are of 162, 205, 252, 276μm depths with 6, 10, 15 and 20 μm diameters respectively, prepared by Multiplex Inductively Coupled Plasma (ICP) etching. It was shown that there are very differences in process of high aspect ratio microstructures between the deep pores, a closed structure, and deep trenches, a open structure. The morphology and the aspect ratio dependent etching were analyzed and discussed. The macroporous silicon etched by ICP process yield an uneven, re-entrant, notched and ripples surface within the pores. The main factors effecting on the RIE lag of HARP etching are the passivation cycle time, the pressure of reactive chamber, and the platen power of ICP system.

The design of cathode for organic photovoltaic devices

We have discussed the effect of the residual gas in the Al metal cathode deposition process and consequently influence the performance of organic photovoltaic devices (such as organic photoelectron detector or solar cell). We believe that the origin of degradation in Jsc and FF from the Al cathode device should be the formation of AlOx in the C60-Al interface, which contaminate the interface and plays a role like an energy barrier that block the charge collect process. To solve this problem the Ag and Alq3 layer had been inserted before the Al. Owing to the advantageous of Alq3 and Ag layer, the device which Al cathode prepared at a lower vacuum condition exhibits a comparable performance to that device which Al cathode deposited in regular situation. As an additional benefit, since the introducing of Alq3/Ag layer in the VOPc/C60 organic photovoltaic device performs a better near-infrared response, this phenomenon has been confirmed by means of both simulation and experimental data. So the design of our new cathode structure provides a degree of freedom to modulate the light absorption for organic photovoltaic devices in short-wave and long-wave.

Simulation of multiplying electron distribution in electron multiplier layer for EBAPS

The multiplying electron distribution within the electron multiplier layer for electron bombarded active pixel sensor (EBAPS) was simulated. The photoelectron scatting trajectories in electron multiplier layer were simulated based on the low-energy electron-solid interaction model and Monte Carlo method. According to semiconductor theory, the influence factors (the incident electron energy, depth and beam diameter) how affecting the energy loss rate were studied. Therefore, the photoelectron scatting trajectories and multiplying electron distribution in electron multiplier layer can be simulated, which will provide theoretical basis to further simulate the charge collection efficiency of EBAPS.

Structure release of silicon micro-channel based on wet etching

Based on wet etching theory, the silicon microchannel structure after electrochemical etching was released in TMAH solution to obtain the through-hole microchannel. The silicon wafer with the different resistivity was selected as the substrate of microchannel plate, the TMAH solution was selected in mass concentration of 28.5wt%, and the SiO2 passivation layer with the thickness of 200nm was prepared by thermal oxidation for protection of side-wall of microchannel. Contrary to the problem encountered in wet etching, Firstly, the corrosion characteristics of silicon and SiO2 thin film in TMAH solution were investigated, respectively. In addition, the effects of the pH values of TMAH solution on corrosion characteristics in microstructure releasing of silicon microchannel were studied and analyzed. The experiments show that the silicon wafer with high resistivity can be easily etched, the etching rate of SiO2 film in TMAH is uniform, and adjusting the pH value of etching solution to make it constant during etching can effectively increase the corrosion rate and decrease the surface roughness of samples.