Preparation method of GaN-based low-order surface grating DFB laser

Abstract

The invention discloses a preparation method of a GaN-based low-order surface grating DFB laser. The method comprises the following steps: depositing a SiO2 mask on an epitaxial wafer of the GaN-basedlaser; preparing uniform Bragg gratings on the surface of the substrate by using a nanoimprint technique, fabricating strip patterns by photolithography, and forming a composite structure of ridges and gratings; etching the GaN, and etching the epitaxial wafer through a strip photoresist and the grating SiO2 composite structure mask to form a surface composite grating structure having ridges; andpreparing upper and lower electrode structures of a laser chip to obtain a GaN-based DFB semiconductor laser. The method etches the ridge patterns required by the grating preparation and at the laterstage of the process at the same time, and combines the nano imprint template and the lithography pattern design respectively, which can design and prepare GaN-based DFB lasers with different wavelengths, different order gratings and different sizes, and can greatly reduce the cost of GaN-based DFB semiconductor lasers and effectively improve the uniformity of products.

Description

technical field [0001] The invention belongs to the field of semiconductor optoelectronic devices, relates to a GaN-based DFB semiconductor laser, in particular to a preparation method of a GaN-based low-order surface grating DFB laser. Background technique [0002] Information transmission requires a stable single-mode laser, and this application requirement promotes the research and development of semiconductor lasers. When a semiconductor laser is used as a light source in a communication system, if it has dispersion, the spectral broadening will reduce the transmission bandwidth, thereby limiting the transmission rate. Distributed feedback (DFB) semiconductor laser is the core device of the transmitting end in the optical communication system. The Bragg grating is used to effectively select the resonant mode. The resonant cavity loss of different wavelengths of lasers is quite different, so it can still maintain complete singleness in the case of high-speed modulation. ...

AI Technical Summary

Problems solved by technology

For GaN-based DFB lasers, the grating period is about a hundred nanometers. One of the usual methods is electron beam exposure, but the grating area prepared by this method is small. If a large-area grating at the epitaxial wafer level is prepared, the electron beam exposure will take a long time. , the splicing accuracy of the writing field is difficult to guarantee, and the cost is too high; or a short-period grating structure is prepared by means of deep ultraviolet laser double-beam interference exposure. After exposure and development, the grating pattern is transferred to the semiconductor material by chemical etching or reactive ion etching. , but deep ultraviolet lithography has high requirements on the performance of the lithography machine

[0005] In short, the existing embedded grating DFB laser has the problem of difficult material regrowth, resulting in low yield and high cost

Moreover, the existing surface grating DFB lasers have problems such as high equipment requirements, high cost and inability to prepare large-area devices.

The above problems are also bottlenecks that limit the mass use of GaN-based DFB lasers

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