AlGaNGaN异质结材料特性与HEMT器件研究

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1、摘要摘要常规半导体微波功率器件已经发展到其性能极限。为了满足无线通信的未来需求，宽禁带半导体GaN和SiC成为研究的热点。AIGaN／GaNHEMT器件被认为是1．50GHz频率范围内的理想的微波功率器件。然而，目前AlGaN／GaNHEMT器件物理和工艺技术还不成熟。本文即在此背景下写作的。首先，基于ISETCAD模拟结果以及文献中的大量数据，分析了AIGaN／GaN异质结中影响2DEG的因素，如A1GaN势垒层极化、Al组分、应变、厚度以及掺杂等。基于静电学分析，抓住主要矛盾忽略了一些细节，得出了

2、表面态是异质结中2DEG的来源。基于这一分析结果解释了模拟和文献中的大量数据。最后根据建立物理理论的基本方法对得出的结论进行系统的分类。其次，基于对异质结的深入理解，建立了A1GaN／GaNHEMT的直流特性解析模型。最后，研究了A1GaN／GaNHEMT的电流崩塌效应。着重阐述了应力模型、虚栅模型等几种解释电流崩塌效应形成机理的模型以及表面处理、场板结构、生长盖冒层等减少电流崩塌的措施。关键词：AIGaN／GaN异质结构高电子迁移率晶体管电流崩塌AbstractMicrowavepowerdevic

3、eswitllconventionalsemiconductorshaveapproachedtheirperformancelimits．Microwavepowerdevices、析tllconventionalsemiconductorshaveapproachedtheirperformancelimits．Tomeetthefutureneedinwirelesscommunications，researchefforthasbeendirectedtowidebandgapsemicond

4、uctors，suchasGaNandSiC．A1GaN／GaNHigh-Electron-Mobility—Transistors(HEMT)areregardedastheidealmicrowavepowerdevicesin1-50GHzfrequencyrange．HoweveLthedevicephysitsandthefabricationtechnologyofA1GaN／GaNHEMTremainimmature．Thisdissertationiswritteninthebackg

5、round．A1GaN／GaNHigh·-Electron··Mobility·-Transistors(HEMT)areregardedastheidealmicrowavepowerdevicesin1-50GHzfrequencyrange．However，thedevicephysicsandthefabricationtechnologyofA1GaN／GaNHEMTremainimmature．ThisdissertationiswriReninthebackground．Firstly,

6、basedontheresultsofISETCADsimulationandalargeamountsofpublisheddata,analysisofmanyfactorstllatinfluenceonthedensityoftwodimensionalelectrongassuchaspolarity,alloycomposition,strain，thickness，anddopingoftheA1GaNbarrier．Basedontheelectrostaticsanalysis，re

7、gardlessofthedetailstoseizethemainpoints，surfacestatesareidentifiedasanimportantsourceofelectronsisobtained．TheresultsofISETCADsimulmionandalargeamountofpublisheddataareinterpretedbythistheory．Then，theconclusionsareclassifiedbymethodoftheestablishmentof

8、theoreticalphysics．Secondly,basedonthedeepresearchofAlGaN／GaNheterostructm'es，ananalyticalmodelfortheDCcharacteristicsofAlGaN／GaNHEMTisdeveloped．Finally,currentcollapseofA1GaN／GaNHEMTisresearched．Thereasoncausedthecurrentcollapse