Method and apparatus for expanding growth of AlN single crystal

Abstract

The invention discloses a method and apparatus for expanding growth of an AlN single crystal. Homogeneous expanding growth is performed through a small seed crystal by using a specially-made thermal field adjusting component and an iterative growth technology, and epitaxial expanding from a small size to two inches or even a larger size can be realized. The specially-made thermal field adjusting component is an internal concave component with an axisymmetric structure, is made of metal tungsten, is internally provided with atmosphere, and is used for creating a bent temperature field and providing a radial temperature gradient, so that the expanding growth of the seed crystal can be realized. According to the method and apparatus, the expanding efficiency is high; the dislocation density and impurity concentration in the crystal in the expanding iterative growth are gradually reduced, and multiple iterative growth effects are superposed, so that the effects of further increasing the size and gradually improving the crystal quality can be realized at the same time; and an expanding structure is located outside a crucible, is not in contact with the crystal, is beneficial to repeateduse and reduction of the growth cost, is simple and easy to manufacture, and can be applied to industrialization of crystal preparation.

Description

technical field [0001] The present invention relates to the field of crystal growth technology, in particular to a method and device for preparing a seed crystal or substrate grown by diameter expansion of AlN single crystal physical vapor transport method (PVT method), which is a method based on multiple iterations of diameter expansion growth. AlN growth technology. Background technique [0002] Because the lattice constant and thermal expansion coefficient of AlN (aluminum nitride) are very close to AlGaN (aluminum gallium nitrogen) with high Al composition, AlN single crystal as a homoepitaxial substrate can significantly reduce the dislocation density of the epitaxial layer and improve the lattice quality. To further improve the internal quantum efficiency of the device, it has become the best substrate for epitaxial growth of AlN and AlGaN to make deep ultraviolet optical components, including deep ultraviolet light-emitting diodes, laser diodes and deep ultraviolet de...

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Problems solved by technology

[0003] At present, international research groups have been able to obtain 2-inch high-quality AlN single crystal substrates with low dislocation density through the PVT method, but they are faced with problems such as difficulty in cultivating seed crystals, low efficiency of epitaxial diameter expansion, and poor repeatability. AlN single crystal is difficult to industrialize and the price is very expensive

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