Synthesis method and synthesis container of phosphorus-silicon-cadmium polycrystal

Abstract

The invention relates to a synthesis method of a phosphorus-silicon-cadmium polycrystal. High-purity phosphorus, silicon and cadmium are used as raw materials, the mol ratio of silicon:cadmium:phosphorus is 1:1:2, and the phosphorus can be properly enriched. The method comprises the following steps: (1) cleaning and drying the synthesis container; (2) charging; and (3) synthesizing by a combined method of two-region timely temperature monitoring, low-temperature gas phase transportation and separation and high-temperature mechanical and temperature oscillation, and inhibiting the decomposition of the product in a gradient cooling mode after the synthesis finishes. The synthesis container is composed of an inner layer crucible and an outer layer crucible, wherein the inner layer crucible in the working state is a silica tube of which both ends are closed, and the two closed ends are respectively provided with a support bar; the outer layer crucible in the working state is a silica tubeof which both ends are respectively closed by a support sleeve; the inner layer crucible is positioned in the outer layer crucible; the support bars arranged on the two closed ends are respectively inserted into the support sleeves on the two ends of the outer layer crucible; and the outer wall of the inner layer crucible and the inner wall of the outer layer crucible form an annular gas chamber.

Description

technical field [0001] The invention belongs to the field of preparation of ternary compound semiconductor materials, and in particular relates to a method for preparing a phosphorus-silicon-cadmium polycrystal and a used container. Background technique [0002] Cadmium silicon phosphorus (CdSiP 2 ) crystal is a new type of infrared nonlinear optical material with excellent performance, which has broad application prospects in the fields of infrared countermeasures, laser radar, laser communication and national defense technology. [0003] Synthesis of CdSiP 2 Polycrystalline is carried out in a closed quartz crucible, due to the high phosphorus vapor pressure (about 20atm at 550°C) and the CdSiP 2 The high dissociation pressure (about 22 atm) of polycrystal at the melting point temperature can easily cause the explosion of the quartz crucible, making the synthesis very difficult. Currently synthesized CdSiP 2 The methods of polycrystal mainly include: 1. Halogen assiste...

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Problems solved by technology

Among them, the halogen-assisted gas phase transport method and the tin melt growth method need to add halogen (halide) or tin in the synthesis to reduce the synthesis temperature and thereby reduce the pressure in the crucible, so that the synthesis product is polluted, and the prepared single crystal cannot meet the requirements of device manufacturing. Requirements; two-temperature-zone gas-phase transport method puts Cd and Si in a graphite boat coated with pyrolytic boron nitride, puts the graphite boat on one end of the quartz crucible, and then places P on the other end of the quartz crucible. The low temperature at the P end and the high temperature at the graphite boat end make P gas transport and react with Cd and Si to form CdSiP 2 Polycrystalline, the whole process needs to maintain horizontal operation, the main disadvantages of this method are: 1. Synthesis of intermediate product CdP 2 , Cd 2 P 3 It is easy to condense on the low-temperature end of the quartz crucible, causing the crucible to rupture and cause an explosion; 2. The gas phase reaction product may wrap the unreacted substance, making it difficult to continue the reaction. The existence of the graphite boat prevents the materials from being fully mixed, and cannot ensure sufficient and complete synthesis; 3. Synthesized CdSiP 2 Polycrystals are easy to decompose during the cooling process, and the purity of the product cannot be guaranteed

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