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采用有机金属化学气相沉积法,在1μm氮化铝/蓝宝石衬底上制备了不同结构的AlGaN基多量子阱结构的深紫外发光二极管,其禁带边发光峰位为264 nm。使用透射扫描电镜对器件的结构进行了表征,测试了器件的光学和电学性能。通过分析电致发光谱得出:在器件活性区域和p型AlGaN盖层之间插入1 nm i-AlN电子阻挡层的样品其位于320 nm处的寄生发光峰能被有效抑制,该杂质峰主要是由于电子溢出至p型盖层,与处于Mg相关的受主深能级上的空穴复合所致。此外,验证了该电子阻挡层对发光特性具有一定的改善效果。通过优化UV-LED结构以及合理设定外延层的厚度参数,可以使其出光功率提高一个量级。
A deep-ultraviolet LED with different structure of AlGaN-based MQW structure was fabricated on 1μm AlN / sapphire substrate by metalorganic chemical vapor deposition. The bandgap emission peak was 264 nm. The structure of the device was characterized by transmission electron microscopy and the optical and electrical properties of the device were tested. The analysis of electroluminescence shows that the sample with 1 nm i-AlN electron barrier layer inserted between the active region of the device and the p-type AlGaN cap layer can effectively suppress the parasitic luminescence peak located at 320 nm, which is mainly Is due to the electrons spilling over the p-type cap layer and recombining with the holes at the acceptor deep level associated with Mg. In addition, it is verified that the electron blocking layer has a certain improvement effect on the light emitting characteristics. By optimizing the UV-LED structure and the reasonable setting of the thickness parameter of the epitaxial layer, the output power can be increased by an order of magnitude.