報告題目：Lateral polarity control of III-nitride thin films and applications in optoelectronic/electronic devices
報告人：郭 煒 中國科學院寧波材料技術與工程研究所副研究員
報告時間：2018年1月25日 9:30-11:30
報告地點：北辰校區(qū)西教二-407
報告簡介：
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.
報告人簡介：
郭煒，博士，中國科學院寧波材料技術與工程研究所副研究員。2010于上海交通大學獲得學士學位，2014年于美國北卡羅來納州立大學獲得博士學位。2015年在美國應用材料有限公司（Applied Materials Inc）擔任工藝工程師，2016年2月加入中國科學院寧波材料技術與工程研究所任特聘青年研究員。郭博士長期從事氮化物外延生長、光電器件發(fā)光調(diào)控的工作，特別是基于AlN自支撐襯底進行同質(zhì)外延生長和AlGaN基深紫外LED和激光二極管（LD）的研究?；貒?，郭博士主要致力于氮化物新型結(jié)構(gòu)的設計、制備和光電性能的探索，方向包括氮化物極性調(diào)控、光子晶體LED、等離子體基元增強紫外LED等。郭博士目前作為項目負責人承擔國家自然科學基金、浙江省錢江人才基金、浙江大學開放課題基金、寧波市鎮(zhèn)海區(qū)人才推薦項目等多個課題，作為子課題負責人承擔科技部重點研發(fā)計劃一項。郭博士在Nanoscale, ACS Nano, Applied Physics Letters, Journal of Applied Physics, Journal of Crystal Growth等雜志發(fā)表論文26篇，申請發(fā)明專利7項。
