发光均匀、低热堆积的高性能InGaN基绿光LD的研究

InGaN基蓝绿激光二极管(LD)由于其辐射光相应于海水低损耗窗口波长，因此被认为在对潜通信、水下探测和水下传感等领域有着广阔的潜在应用前景。然而，目前其较低的光学性能仍难以满足实际需要，尤其是长波长（绿光）InGaN基LD。这主要被归因于高铟组分诱发的结晶质量的降低和阱/垒界面应力的增加，以及激射条件下脊下方局部区域位错缺陷相关的非辐射复合中心的增加以及漏电流和杂质粒子扩散的增强。前者导致了发光均匀性和发光效率的降低，而后者则是导致器件性能退化的主要原因。本项目拟在传统InGaN基蓝光LD结构的基础上，通过进一步优化结构参数和生长工艺（如采用应力释放、生长中断、In蒸发抑制、低温P型波导层及超晶格覆盖层等工艺），来增加In并入率、抑制富In团簇形成、提高器件结构质量等，以获得发光均匀、低热堆积的高性能InGaN基绿光LD，并同时阐明其复合发光和退化失效的内部物理机制。

InGaN-based blue-green laser diodes (LDs) are considered to have broad potential applications in submarine communications, underwater detection and underwater sensing because of their emissions corresponding to the low loss window wavelengths of seawater. However, at present, its low optical performance still can not meet the actual needs, especially the long wavelength (green) InGaN-based LD. This is mainly attributed to the decrease in crystalline quality and increase in stress at the well/barrier interface induced by high In content, and to the increase of the non-radiative recombination centers, and enhancements of the leakage current and impurity particle diffusion in the local regions under the ridge during device operation, due to the presence of the dislocations or defects. The former results in the decrease of luminescence uniformity and efficiency, the latter is the main cause of device degradation. In this project, to obtain the high-performance green InGaN-based LDs with homogeneous luminescence and low thermal budget, the structure parameters and growth processes will be further optimized (such as using stress release, growth interruption, suppression of In evaporation, adjustment of well thickness, low-temperature p-typed waveguide ayer and superlattice cladding layer and so on) on the basis of the traditional InGaN-based blue LDs, for reducing internal strain, increasing In incorporation rate, suppressing formation of In-rich cluster, improving the structural quality of LD and so on, at the same time, the internal physical mechanisms of the raditive recombination and degeneration failure of the structure are clarified.