报告题目：Lateral polarity control of III-nitride thin films and applications in optoelectronic/electronic devices
报告人：郭 炜 中国科学院宁波材料技术与工程研究所副研究员
报告时间：2018年1月25日 9:30-11:30
报告地点：北辰校区西教二-407
报告简介：
There is a growing demand for mercury-free, environmentally friendly, compact ultraviolet (UV) LEDs for applications such as water/air disinfection, bio-sensing, and epoxy curing. The AlxGa1-xN (0£x≤1) alloy has a tunable bandgap from 3.4 to 6.1 eV which coversalmost the entire UV spectral region from 360 to 210 nm,making it particular suitable for the realization of UV-LEDs. However, the UV-LED performance has not yet reached to the level obtained in highly commercialized InGaN-based blue LED counterpart.
Here, we demonstrate a new approach to enhance the luminescence of UV-LEDs via the introduction of AlGaN/GaN multiple quantum wells (MQWs) consisting of both III-polarity and N-polarity domains, forming a lateral-polarity-structure (LPS). The LPS-MQW with precise control of the domain dimension is achieved via a pre-patterned AlN buffer layer on sapphire substrates.Enhanced luminescence from LPS MQW is attributed to a synergetic effect of 3D nature of MQW, lateral confinement of carriers due to variation in QW thickness and surface potential differences. Direct polarity determination of AlGaN/GaN MQWs was realized through HR-STEM. This work suggests that the introduction of LPS in AlGaN-based MQWs can provide unprecedented tunability in achieving higher luminescence of such emitters.
In addition to LPS-based UV-LEDs, the application of LPS in GaN-based Schottky Barrier Diode (SBD) will also be briefly discussed. SBDs are fabricated on LPS GaN as well as conventional undoped GaN. Current-voltage (I-V) characteristic revealed that the SBD fabricated on LPS GaN has higher forward current, barrier height closer to 0.7 eV, and ideality factor closer to unity compared to SBD fabricated on conventional GaN, demonstrating a novel approach for the development of high-performance SBD with low on-state resistance (Ron) and high rectification ratio.
报告人简介：
郭炜，博士，中国科学院宁波材料技术与工程研究所副研究员。2010于上海交通大学获得学士学位，2014年于美国北卡罗来纳州立大学获得博士学位。2015年在美国应用材料有限公司（Applied Materials Inc）担任工艺工程师，2016年2月加入中国科学院宁波材料技术与工程研究所任特聘青年研究员。郭博士长期从事氮化物外延生长、光电器件发光调控的工作，特别是基于AlN自支撑衬底进行同质外延生长和AlGaN基深紫外LED和激光二极管（LD）的研究。回国后，郭博士主要致力于氮化物新型结构的设计、制备和光电性能的探索，方向包括氮化物极性调控、光子晶体LED、等离子体基元增强紫外LED等。郭博士目前作为项目负责人承担国家自然科学基金、浙江省钱江人才基金、浙江大学开放课题基金、宁波市镇海区人才推荐项目等多个课题，作为子课题负责人承担科技部重点研发计划一项。郭博士在Nanoscale, ACS Nano, Applied Physics Letters, Journal of Applied Physics, Journal of Crystal Growth等杂志发表论文26篇，申请发明专利7项。
