A kind of epitaxial wafer structure and its surface roughening method

Abstract

The invention provides an epitaxial wafer structure comprising a substrate, a buffer layer, a first type nitride layer, a luminescent layer and a second type nitride layer. The buffer layer, the first type nitride layer, the luminescent layer and the second type nitride layer are successively formed on the substrate. The second type nitride layer includes a first nitride layer and a second nitride layer, wherein the first nitride layer and the second nitride layer are successively formed on the luminescent layer; the second nitride layer is a heavy-doping nitride layer; and pits are distributed on the surface of the second nitride layer. According to the invention, the heavy-doping nitride layer is added on the epitaxial wafer and chemical corrosion is carried out on the surface of the heavy-doping nitride layer. Because the doped impurity concentration of the heavy-doping nitride layer is high and defects are easily formed and thus the corrosion speed at the defected places is fast, thereby forming pits at the surface of the epitaxial wafer and achieving an objective of epitaxial wafer surface roughening. Therefore, the luminous efficiency of the epitaxial wafer can be effectively improved.

Description

technical field [0001] The invention belongs to the field of semiconductors, in particular to a method for roughening an epitaxial wafer. Background technique [0002] Light-emitting diode (LED) is a junction-type electroluminescent semiconductor device that can convert electrical signals into optical signals. Due to the large refractive index difference between the material used to make LEDs and the outside air, for example, blue light, green light and white light are currently produced. The main material of LED is III-V gallium nitride. The refractive index of gallium nitride material is about 2.5, while the refractive index of external air is 1. With such a large difference in refractive index, a large amount of light is reflected back during the propagation of light from an optically denser medium to an optically thinner medium, and finally disappears in the LED chip in the form of heat, which does not contribute to the luminescence of the LED, but instead causes the LED...

AI Technical Summary

Problems solved by technology

With such a large difference in refractive index, a large amount of light is reflected back during the propagation of light from an optically denser medium to an optically thinner medium, and finally disappears in the LED chip in the form of heat, which does not contribute to the luminescence of the LED, but instead causes the LED The internal temperature of the chip rises, which affects the life and luminous efficiency of the LED

[0003] Now, there is a way to improve the light output by roughening the surface of the LED chip, which is mainly to roughen the contact surface between the optically dense medium and the optically sparse medium, and to improve the light output efficiency of the LED chip by changing the incident angle. Usually, ICP is used. Bombarding the surface of the LED to achieve the purpose of roughening, which requires relatively expensive ICP etching equipment, and the production cost is relatively high

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