System and method for growing uniform nitride single crystal by flux method

Abstract

The invention discloses a system and a method for growing uniform nitride single crystals by a flux method. The system comprises a single crystal growth unit, a raw material circulation unit, a stirring unit and a nitrogen supply unit, the single crystal growth unit comprises a reaction chamber for reacting and growing nitride single crystals, the raw material circulating unit comprises a circulating chamber for accommodating raw materials required for growing the nitride single crystals, the reaction chamber is communicated with the circulating chamber, and the raw materials can circularly flow between the reaction chamber and the circulating chamber; the stirring unit is at least used for stirring raw materials in the circulating chamber and / or the reaction chamber; and the nitrogen supply unit is at least used for supplying nitrogen into the circulating chamber and / or the reaction chamber. The raw material circulating unit and the stirring unit are used for circulating and stirring the raw materials in the reaction chamber and the circulating chamber, so that the uniformity of the grown nitride single crystal is better, and the quality is higher.

Description

technical field [0001] The invention relates to a system for growing a gallium nitride single crystal, in particular to a system and method for growing a uniform nitride single crystal by a flux method, and belongs to the technical field of single crystal material growth. Background technique [0002] As one of the core materials of the third-generation semiconductors, gallium nitride has a large band gap, high electron mobility, high breakdown field strength, high thermal conductivity, small dielectric constant, strong radiation resistance, and good chemical stability. and other excellent characteristics. Gallium nitride is used in a wide range of optical devices and high-power electronic devices, such as light-emitting diodes (LEDs), laser diodes (LDs), and high-power transistors. At present, there are mainly four methods for producing GaN single crystal substrates, high-pressure melt method, hydride vapor phase epitaxy method, ammonothermal method, and flux method. [0...

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Problems solved by technology

[0004] Sodium metal acts as a flux to promote the N 2 The N≡N triple bond is broken to form a nitrogen ion (N 3- ), so that nitrogen ions dissolve in molten gallium metal, increase the solubility of nitrogen ions in molten metal gallium, and promote the growth rate of gallium nitride single crystal, however, due to the solubility of nitrogen ions near the liquid surface of molten metal gallium Larger, it is easy to make the melt in this area become a supersaturated state, so that the nucleation and growth of this local area will result in an excessively high nucleation rate, and more small grains will be obtained, which is not conducive to the flux method GaN bulk single crystal Liquid phase epitaxial growth; carbon element can inhibit the generation of polycrystals on the crucible wall to increase the yield of GaN single crystals

[0005] However, during the growth process of GaN, on the one hand, the quality of the grown GaN is not uniform due to the uneven distribution of the molten growth materials of GaN (mainly gallium metal, sodium metal, carbon additives, etc.); aspect, such as figure 1 As shown, the distribution of nitrogen ions in the molten raw material is not uniform, resulting in a large amount of dissolved nitrogen ions in the surface area of ​​the molten raw material, and the dissolved amount of nitrogen gradually decreases from the surface of the molten raw material downwards, resulting in the nitrogen content in the growth system ( Inhomogeneous distribution in the molten raw material) leads to slow growth of GaN single crystal, poor and uneven growth quality

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