Research On The Multiplication Mechanism Of EMCCD

The Electronic Multiplying Charge-Coupled Device (abbr. EMCCD) is a new kind of the Low-Light-Level night vision devices. In the past decades, the developed countries have achieved great successes in this kind of research. The anti-radiation capability was effectively improved and strong light damage was avoided using all solid state multiplying structure. The detection sensitivity was improved and the dark current was suppressed using the Split Gate and Virtual Phase technology. The single photon detection was achieved through the deep refrigeration and appropriate multiplication. However, there are still two problems about EMCCD. (1) There wasn’t a complete mathematical model. It was adverse to further optimization and application. (2) The output time resolution of the LLL image wasn’t high limited by the multiplying state structure. In the mean time, they strengthened the blockade in the aspects of sale and technical support to China, which led our country in the slow process of self-study in this field and keeping a wide gap between home and abroad. Based on the electronic multiplying theory, setting up the whole math model through simulation research and putting forward perfect technology and solutions could make up for the existing problems of EMCCD and improve the theory level and speed up the technology application in our civil each field.Firstly, a structure model of the Charge Carrier Multiplication register (abbr. CCM) was built in this paper. The interface state was avoided by using buried channel in CCM. The signal charge transfer channel was formed in the interaction of the gate and bias voltage to the CCM. The various physical parameters of channel potential were studied by theoretical calculation and modeling simulation, such as gate voltage, bias voltage, the thickness of oxide layer and buried channel, the doping of bulk and buried channel. The optimal parameter sets were obtained by comparison of the simulation results and buried devices. These results were coincided with the actual situation of the device.Secondly, this paper presented the integrated EMCCD multiplication model. In addition to the electric field, there are some other influencing factors, such as the type of materials, lattice direction and working temperature. Based on the analysis of separate factor, the model was optimized by using three necessary parameters, such as the number of multiplication states (N), multiplication gap width (W) and electric field intensity (F). The results were coincided with the multiplication curve of the actual TI device.Finally, two kinds of noise models were built and the corresponding formulas were deduced. The ENF indicates the gain fluctuation degree. Therefor, for further research on EMCCD multiplication performance, the following four performance tests were done. (1) The relation curve between the EM-DAC and the real gain was tested. The results indicated the non-linear relation in between. (2) The unique serial clock induced charges (abbr. CIC) in EMCCD were tested. The quantity level of CIC obtained by background noise testing was 0.01～0.1rms/pixel, slightly higher than the readout noise. (3) We calculated the matching coefficient of typical objects with three kinds of EMCCD in the night sky. Superior matching performance determined the high sensitivity to LLL objects. (4) We calculated the multiplication image uniformity. The tested results reached about 1% according to two kinds of EMCCD with same resolution for fixed gain (300). The results showed the high-end EMCCD’s gain fluctuation degree.In the end of this paper we drew four pieces of conclusion. (1) Silicon detector should be the foundation to realize the multiplication gain. (2) The CCM should use shallow doping and abrupt profiles. (3) The device should choose a single style carrier. (4) The system should use the single-weak-gain and the multistage multiplying. In view of the shortcomings in the research, we put forward the future prospect of development and research about electron multiplying technology.