Patterned sapphire substrate with nonpolar and semipolar surface, visual light communication light source with nonpolar and semipolar surface and preparation method thereof

Abstract

The invention discloses a visible light communication light source based on a nonpolar and semipolar surface and a corresponding patterned sapphire substrate. A sapphire substrate is selected to be processed into grating-shaped strip-shaped patterns; the angle of the side wall of a step is optimized in the etching process, and the angle of a growth surface of the next step is optimized; a barrierlayer is designed on the patterned sapphire substrate, and a silicon oxide film is adopted as an epitaxial barrier layer; a GaN layer, an N-type GaN layer, an InGaN / GaN multi-quantum well layer, an electronic barrier layer and a p-type GaN layer are sequentially grown by adopting a chemical vapor phase epitaxy method, and the growth method of the GaN layer, the N-type GaN layer, the InGaN / GaN multi-quantum well layer, the electronic barrier layer and the p-type GaN layer is disclosed. The influence of quantum-limited Stokes effect is weakened by utilizing the advantages of non-polar / semipolarsurface on III-group nitride polarization regulation, the overlapping of electron-hole wave functions on real space is increased, and the radiation recombination proportion and the rate of current carriers are improved, and therefore, the method provided by the invention is suitable for effectively improvement of the visible light communication performances by adopting the nonpolar and semipolar surface technologies.

Description

technical field [0001] The invention relates to a patterned sapphire substrate with non-polar and semi-polar surfaces, a light source for visible light communication and a preparation method thereof, belonging to the field of visible light communication. Background technique [0002] At present, the modulation bandwidth of GaN-based LEDs epitaxy on c-plane sapphire is only a dozen megahertz (MHz) to tens of megahertz, which fundamentally restricts the communication rate of VLC integrated chips. The modulation bandwidth of the LED is mainly determined by the RC time constant and the recombination lifetime of the carrier radiation. By reducing the size of the LED, the junction capacitance and the RC time constant can be effectively reduced, thereby improving the modulation bandwidth of the LED. However, this method also It will reduce the light output power of the LED; another way to increase the modulation bandwidth of the LED is to reduce the carrier radiation recombination ...

AI Technical Summary

Problems solved by technology

The modulation bandwidth of the LED is mainly determined by the RC time constant and the recombination lifetime of the carrier radiation. By reducing the size of the LED, the junction capacitance and the RC time constant can be effectively reduced, thereby improving the modulation bandwidth of the LED. However, this method also It will reduce the light output power of the LED; another way to increase the modulation bandwidth of the LED is to reduce the carrier radiation recombination lifetime. Studies have shown that the relationship between the modulation bandwidth of the LED and the current density is close to a linear relationship. With the increase of the current density, the load The recombination lifetime of the carriers gradually decreases, but when the current density is too large, the LED will have the Droop effect, which restricts the further improvement of the modulation bandwidth

On the other hand, although InGaN-based multi-quantum well visible light detectors have made some progress, they still face some challenging issues in order to achieve large-scale commercialization, such as poor quality of epitaxial layer materials, high background carrier concentration and insufficient light absorption. At present, InGaN-based detectors still have problems such as slow response speed, and there is still a relatively large gap between the device performance level and commercial silicon-based photodetectors. These problems restrict the further improvement of the communication rate of visible light communication integrated chips.

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