氮化镓激光器具有高速调制特性，其中分布反馈（DFB）激光器利用布拉格光栅实现单纵模工作，在可见光通信系统和激光制冷应用中被广泛使用。目前，380-450nm的单频激光主要依靠长波长激光器倍频实现，是由于该波段对应的布拉格光栅周期低于100nm，精密光栅的制备和光栅上的高质量氮化物二次外延是两大制约因素。本项目旨在GaN基片上制备出布拉格光栅，利用高温金属有机物气相外延（MOCVD）设备实现AlGaN薄膜二次外延，解决氮化镓基DFB激光器制备的核心问题之一。研究不同光栅深度、占空比等光栅参数对纳米异质外延的影响规律，同时，通过分步生长的方式观察二次外延成核、生长过程，对金属原子表面迁移长度低于光栅周期的生长进行动力学分析，得到短周期光栅二次外延生长机理。纳米异质外延是当前氮化物光电器件研究最前沿的课题之一，不仅能为纳米结构增强半导体器件性能提供技术支撑，同时在材料物理方面具有重要的研究意义。

Gallium nitride laser own the advantage of high speed modulation, especially distributed feedback lasers (DFB) developed the single-mode by using Bragg grating, which could be applied to communication systems and laser cooling. For the 380-450nm blue-violet light, the value of a period of the first-order diffraction grating is under 100 nm. Its challenge lies in that form the narrow line width grating target and nitride overgrowth based on the Bragg grating. Here we propose to fabricate the fine step shape structure of first-order grating by the nanoimprint and inductively coupled plasma (ICP) dry etching and carry out overgrowth high quality AlGaN film by metalorganic chemical vapor deposition (MOCVD). Then a series of grating with same period and different depth and duty ratio would be designed and fabricated, and improve the overgrowth on these Bragg gratings to study the influence of grating structure to the nano-heteroepitaxy. Moreover, we observe the nucleation and growth process by step-by-step growth to study the growth mode for nitride overgrowth on grating, under the condition that the grating period is larger than the mental migration length on the surface. The growth dynamics analysis of the nitride nano-epitaxy is one of the frontier areas of nitride photoelectric device, which is not only provide technical support for semiconductor device performance with nanostructure, but also have important research significance in semiconductor material physics.