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Explanation

GaAs single crystal is grown by horizontal Bridgman method. It is the main variety of GaAs single crystal, accounting for 60% to 70% of the total amount of GaAs single crystal. The growth equipment is relatively simple, including a horizontal furnace with three or more temperature zones, mechanical transmission devices, and temperature control systems. In the horizontal Bridgman method, high-purity As and the boat containing Ga are sealed at both ends of the quartze reaction tube. By controlling the temperature at the As end (about 610 ° C, when the vapor pressure of As is 0.1MPa), a certain As pressure is maintained in the reaction tube. GaAs single crystal are grown in the high temperature region (1245 ° C to 1260 ° C), using a certain temperature gradient. There is usually one or more intermediate temperature zones between the high-temperature and low-temperature zones, which helps to reduce the temperature gradient within the system and suppress silicon (Si) pollution. Compared with other growth methods, the single crystal produced by horizontal Bridgman method usually has a lower dislocation density, which is 0.5 to 1 order of magnitude lower. The dislocation density of Si doped horizontal GaAs grown by this method can be lower than 10 ^ 2 cm ? 2。 In the growth process, As pressure is easy to control, and the chemical composition of single crystal is well controlled. In addition, this method is easily doped with Fe, Si, Zn and other impurities, and is suitable for growing various doped GaAs and semi insulating single crystal.

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Classification