The Purification Of CdSe Raw Material And The Computer Programming Realization To Protract Single Crystals' Standard Pole Figures

Nuclear radiation detector is an important detect device for experimental nuclear physical technology, which has an indispensable role in science research, nuclear safety, environmental monitoring, nuclear medicine, space aviation and mining industry fields. It's also important for nuclear physics. Currently, room temperature semiconductor nuclear radiation detector becomes the emphasis of nuclear radiation detector research and development in many countries for its good energy resolve, high detect efficiency, little bulk, light weight and its portability. As a promising semiconductor material for room temperature nuclear detector, CdSe once received the extensive concern and some preliminary research results, but it didn't get a full development with the reason that high quality single crystal couldn't be produced. Through investigating fully and combining the specific laboratory conditions, our research lab have carried out thorough research aiming at the growth of CdSe single crystal and the preparation of nuclear radiation detector. In order to fabricate eligible detector, growing out high quality single crystal is the first thing. Because of high melting point and easy volatilization, it is difficult to grow out an eligible CdSe crystal with the traditional melt measures. Experiment shows that growing CdSe single crystal by vapor phase method is an simple and effective measure, which puts forward very high requirement for the raw material. If it contains many impurities, crystal growth will be impossible. Furthor more, the impurities will affect the semiconductor carrier concentration, carrier mobility and minority carrier lifetime directly, which are important parameters for the material used for fabricating detectors. The impurities also influence the properties of detectors, such as current leakage, electric charge collect, stability and so on, which will eventually impair the performance of devices. So before crystal growth and detector fabrication, the raw material must be purified and be analyzed by specific method that is the preparation for providing data basis for later work and the total grasp of the effect of purification. This is an emphasis of this research work. Through devising purification technology, CdSe raw material suitable for single crystal growth has been obtained, and through purification method improvement, good recovery rate of raw material and low produce cost also has been obtained. The results of trace impurities analysis by inductively coupled plasma mass spectrometry (ICP-MS) showed that the purity of the material after purification was very high and the CdSe purified by this technique can be used for growing large and high quality single crystals. Although high quality single crystal has been obtained, there are many steps from single crystal to finished product detector. Cutting is a very important step of this process. In order to finish this cutting step successfully, the standard pole figure is an indispensable instructional tool. As for different crystals, they all have a set of standard pole figures belong to themselves, CdSe is also not an exception. But there are no ready-made standard pole figure of CdSe for reference so that they need to be protracted specially. The process of traditional protracting pole figure is commonly finished by handdraw and repetition goes on aiming at different new crystal. So it is time consuming, energy wasting and very fussy. For the sake of changing this situation and acquiring the standard pole figure of CdSe fast, we protracted thatsuccessfully by programming, conbining computer technology, and sovled the problems to protract other crystalline systems'standard pole figures once and for ever. From the effect of computer drawing, this work has certain innovation. It is also another emphasis of this dissertation. Sichuan University Crystal Laboratory assumed the national 863 program "CdSe Single Crystal Growth and The Room Temperature Nuclear Detector Device Research". As one part of it, this research has reference value for gaining CdSe high pure raw material, crystal process and device fabrication.