King Abdullah University of Science and Technology (KAUST), Photonics Laboratory, Thuwal 23955-6900, Saudi Arabia.
Nanoscale. 2017 Jun 14;9(23):7805-7813. doi: 10.1039/c7nr00006e.
The growth of self-assembled, vertically oriented and uniform nanowires (NWs) has remained a challenge for efficient light-emitting devices. Here, we demonstrate dislocation-free AlGaN NWs with spontaneous coalescence, which are grown by plasma-assisted molecular beam epitaxy on an n-type doped silicon (100) substrate. A high density of NWs (filling factor >95%) was achieved under optimized growth conditions, enabling device fabrication without planarization using ultraviolet (UV)-absorbing polymer materials. UV-B (280-320 nm) light-emitting diodes (LEDs), which emit at ∼303 nm with a narrow full width at half maximum (FWHM) (∼20 nm) of the emission spectrum, are demonstrated using a large active region ("active region/NW length-ratio" ∼50%) embedded with 15 stacks of AlGaN/AlGaN quantum-disks (Qdisks). To improve the carrier injection, a graded layer is introduced at the AlGaN/GaN interfaces on both p- and n-type regions. This work demonstrates a viable approach to easily fabricate ultra-thin, efficient UV optoelectronic devices on low-cost and scalable silicon substrates.
自组装、垂直取向且均匀的纳米线（NWs）的生长对于高效发光器件而言一直是个挑战。在此，我们展示了在 n 型掺杂硅（100）衬底上通过等离子体辅助分子束外延生长的具有自发融合的无位错 AlGaN NWs。在优化的生长条件下，实现了高密度 NWs（填充因子＞95%），从而可以在不使用紫外（UV）吸收聚合物材料进行平坦化的情况下进行器件制造。采用大有源区（“有源区/NW 长度比”约为 50%）嵌入 15 堆叠的 AlGaN/AlGaN 量子盘（Qdisks），展示了发出 ∼303nm 光、具有窄半高全宽（FWHM）（∼20nm）的发射光谱的 UV-B（280-320nm）发光二极管（LEDs）。为了改善载流子注入，在 p 型和 n 型区域的 AlGaN/GaN 界面处引入了渐变层。这项工作展示了一种在低成本和可扩展的硅衬底上轻松制造超薄、高效 UV 光电设备的可行方法。
