一维InN/InAlN渐变核壳纳米线阵列高效近红外发光器件研究

In the outer space environment, wide temperature variations and intense radiation have a serious impact on the reliability and lifetime of near infrared light-emitting devices. Therefore, the InN and its III-nitride alloys which has excellent temperature characteristics and strong radiation resistance offer great potential for highly efficient and stable near infrared light-emitting devices (LED) for space applications. However, the efficiency of near infrared (NIR) electroluminescence (EL) of InN LEDs is very low. The smaller power restricts its application in the outer space. Basing on the realization of the NIR EL of InN film for the first time at room temperature, we found that it has abnormal temperature characteristic that the luminous intensity increases with the increase of temperature. Because nanowire materials has higher lattice perfection and better release of stress, we attempt to adopt the InxAl1-xN electronic barrier layer with polarization effect and InN nanowires of improved interface characteristics coated the component graded InyAl1-yN shell layer to improve the radiative recombination efficiency and light extraction efficiency of InN devices, and then using the InyAl1-yNshell to protect InN active region in favor to improve the radiation resistance of the device. We will carry out the investigation of the formation mechanism and the evolution mechanism of defects, and further understanding the carriers’ regulating characteristics of core-shell nanowires heterostructure to realize the NIR EL of InN nanowires with output power of milliwatt magnitude.

外太空环境温差变化大、空间辐射强，对近红外发光器件的可靠性和寿命产生严重影响，因而采用温度特性优良、抗辐射特性强的InN及其合金制备应用于空间辐射环境的近红外发光器件具有巨大潜力。然而目前InN基近红外发光器件发光效率低、功率很小，制约了其在空间领域的应用研究。项目申请人在国际上首次报道InN薄膜室温下近红外电致发光基础上，发现其具有随工作温度升高发光强度增强的异常温度特性。本项目拟利用纳米线具有良好晶格完整性、更好的释放应力等独特优势，创新地采用带有极化效应的InxAl1-xN电子阻挡层和改进界面特性的一维InN/InyAl1-yN组分渐变核壳纳米线异质结结构，在提高InN纳米线载流子辐射复合效率和光提取效率同时，利用壳层结构对InN有源区的保护进一步提高器件抗辐射能力，开展InN纳米线缺陷形成、演化、湮灭机理及核壳纳米线异质结构的载流子调控规律研究，最终实现毫瓦量级的近红外电注入发光。

目前InN基近红外电注入发光已经初步实现，但是这些InN基发光器件发光效率非常低，功率很小。我们通过Silvaco平台的Atlas器件性能仿真工具建立了p-Si/In1-xAlxN/n-InN近红外电致发光器件的几何模型和物理模型；针对无极化电场情况，探索了In1-xAlxN合金组分及厚度对异质结载流子输运及辐射复合发光特性的影响规律；针对存在极化电场情况，模拟了金属极性面及氮极性面异质结结构中极化电场对异质结能带结构的影响，给出了极化电场调制与载流子辐射复合效率的关系，通过对In1-xAlxN合金组分及厚度的调节可实现对极化电场的调控，进而实现InN层中载流子辐射复合效率的增强，优化了器件结构设计。研究了采用MBE方法在蓝宝石衬底上外延InN纳米线的生长机制，探索了缺陷控制规律并实现了高质量InN纳米线的自组装可控生长，进一步在硅衬底上实现了氮极性面InN自组装纳米线的可控制备，为实现本项目中器件结构设计奠定了基础。基于Silvaco器件性能仿真研究中最佳优化条件，实现了金属极性面p-Si/In1-xAlxN/n-InN纳米线异质结结构的制备，并通过器件结构优化设计，制备出了不同核壳包覆形貌的p-Si/In1-xAlxN/n-InN/In1-yAlyN核壳纳米线异质结结构，实现了InN/In1-yAlyN核壳纳米线异质结的良好整流特性，为提高InN纳米线中载流子的辐射复合效率建立了基础。为了进一步满足后续InN近红外发光器件特性研究工作的需要，我们探索性开展了全氮化物体系p-GaN/In1-xGaxN/n-InN的T型核壳纳米线异质结器件特性研究，为后续InN基近红外器件的实用化提供了新的途径。