A kind of epitaxial structure and growth method of iii-v group nitride

Abstract

The invention discloses an epitaxial structure of III-V nitride and a growth method thereof. The growth method comprises the following steps: providing a patterned substrate; growing an underlying structure of an AlN buffer layer on the patterned substrate, wherein the underlying structure is gradually covered with the patterned substrate from the bottom of the patterned substrate to the top of the patterned substrate, so that the upper surface of the underlying structure trends to be smooth, the underlying structure can bend through partial dislocation due to two-dimensional lateral growth, the AlN buffer is relatively difficult to nucleate and grow on the side face of the patterned substrate in lateral epitaxy, and thus an air layer gap is formed between the underlying structure and the side face of the patterned substrate; continuously growing the AlN buffer layer on the underlying structure until the upper surface is approximately smooth; growing an III-V nitride layer on the approximately smooth AlN buffer layer, thereby improving the epitaxial quality of the III-V nitride layer, reducing the lattice imperfection and promoting the luminous efficiency.

Description

Technical field [0001] The invention relates to the technical field of semiconductor materials, in particular epitaxial III-V group nitride materials on a patterned substrate. Background technique [0002] Light-emitting diodes have significant advantages such as long service life, low heat generation, fast response, environmental protection, safety, and small size. Among them, deep ultraviolet light-emitting diodes with wavelengths between 220 and 350 nm have important applications in the fields of biomedicine, anti-counterfeiting identification, water and air purification, etc. [0003] Compared with blue LEDs, the current external quantum efficiency of deep-ultraviolet light-emitting diodes is still low. Taking AlGaN-based deep-ultraviolet LEDs as an example, the main problems are as follows: (1) The piezoelectric polarization and spontaneous polarization of the AlGaN layer are large, and the light emission The layer will be bent violently, reducing the recombination probabilit...

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Problems solved by technology

[0003] Compared with blue LEDs, the external quantum efficiency of deep ultraviolet light-emitting diodes is still low. Taking AlGaN-based deep ultraviolet LEDs as an example, there are mainly the following problems: (1) The piezoelectric polarization and spontaneous polarization of the AlGaN layer are large, and the luminescence The layer will bend sharply, reducing the recombination probability of electrons and holes, resulting in low internal quantum efficiency; (2) As the Al composition increases, the acceptor activation of Mg increases, resulting in an extremely low hole concentration under the cavity; ( 3) As the Al composition increases, the contact barrier between the metal and the AlGaN layer becomes larger, resulting in an increase in contact resistance; (4) Al atomic mobility is low, and as the Al composition increases, the control of two-dimensional growth becomes difficult The larger the , it is difficult to grow an epitaxial layer with a low defect density and a flat surface, which affects the improvement of luminous efficiency

While conventional low temperature (below 1150°C) MOCVD is used for epitaxial growth of AlN, pulse atomic layer deposition is generally used to epitaxial AlN thin film on flat sapphire substrate, or TMIn is used as surfactant to improve the AlN film on flat sapphire substrate. The flatness of the epitaxial AlN film (Chinese patent CN101603172A), but due to the low mobility of Al atoms, it is very difficult to epitaxially grow AlN films on PSS substrates by traditional methods, and Al atoms cannot obtain enough energy to migrate to energy Re-deposition at the lowest point, non-selective growth, the epitaxially grown AlN film is in the shape of protruding hexagonal columns, and it is difficult to obtain a flat epitaxial surface

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