報(bào)告題目：Lateral polarity control of III-nitride thin films and applications in optoelectronic/electronic devices
報(bào)告人：郭 煒 中國(guó)科學(xué)院寧波材料技術(shù)與工程研究所副研究員
報(bào)告時(shí)間：2018年1月25日 9:30-11:30
報(bào)告地點(diǎn)：北辰校區(qū)西教二-407
報(bào)告簡(jiǎn)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(bào)告人簡(jiǎn)介：
郭煒，博士，中國(guó)科學(xué)院寧波材料技術(shù)與工程研究所副研究員。2010于上海交通大學(xué)獲得學(xué)士學(xué)位，2014年于美國(guó)北卡羅來(lái)納州立大學(xué)獲得博士學(xué)位。2015年在美國(guó)應(yīng)用材料有限公司（Applied Materials Inc）擔(dān)任工藝工程師，2016年2月加入中國(guó)科學(xué)院寧波材料技術(shù)與工程研究所任特聘青年研究員。郭博士長(zhǎng)期從事氮化物外延生長(zhǎng)、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(jìn)行同質(zhì)外延生長(zhǎng)和AlGaN基深紫外LED和激光二極管（LD）的研究。回國(guó)后，郭博士主要致力于氮化物新型結(jié)構(gòu)的設(shè)計(jì)、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(qiáng)紫外LED等。郭博士目前作為項(xiàng)目負(fù)責(zé)人承擔(dān)國(guó)家自然科學(xué)基金、浙江省錢(qián)江人才基金、浙江大學(xué)開(kāi)放課題基金、寧波市鎮(zhèn)海區(qū)人才推薦項(xiàng)目等多個(gè)課題，作為子課題負(fù)責(zé)人承擔(dān)科技部重點(diǎn)研發(fā)計(jì)劃一項(xiàng)。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(qǐng)發(fā)明專(zhuān)利7項(xiàng)。
