简介:ThereolutioncharacteristicofGaAs/GaAlAstrransmissionphotocathodeisanimportantparameterinthirdgenerationintensifiers.ThemodulationtransferfunctionofGaAs/GaAlAstransmissionphotocathodeisderivedfromasimpletwo-dimensionaldiffusionequation.Thetheoreticalresolutioncharacteristicofa2μmthickGaAs/GaAlAstransmissionphotocathodeiscalculated.TherelationshipbetweenresolutionandparametersinGaAs/GaAlAstransmissionphotocathodeisdiscussed.AconclusionisshownthatonecandesigntheGaAs/GaAlAstransmissionphotocathodeformaximumquantumefficiency,sincethesacrificeintheresolutiondoesn'tlimitsystemperformances.
简介:<正>基于微电子机械系统的可调谐滤波器和垂直腔表面发射激光器具有宽的连续调谐范围、无偏振灵敏工作和二维陈列集成的独特性能,因而已引起极大关注。但它的一大缺点是需要几十伏的调谐电压,此外由于微机械悬臂是通过静电力向下移动,其实际移动距离仅为实际宽度1/3,所以这种采用静电力的MEMS基滤波器的最大调谐范围受到限制。日本东京技术研究所的微系统研究中心首次研制成功一种具有低调谐电压的新型GaAlAs/GaAs微机械热调谐垂直腔滤波器,由于热应变控制层与加热元件的集成,具有创记录的低至4.7V的调谐电压,并可获得23.2nm的波长调谐。该器件是在上下两层GaAlAs/OaAsDRB之间形成一个空气隙,在上GaAlAs/GaAsDRB上有GaAs或GaAlAs热应变控制层,当施加电压时热应变导致微机械悬臂的移动。当热应变控制层为热膨胀系数较小的GaAlAs时,悬臂向上移动。反之,为热膨胀
简介:Athree-dimensionalmodelofGaAs/A1GaAsquantumdoubleringsinthelateralstaticelectricfieldisinvestigatedtheoretically.Theeigenvalueproblemwiththeeffective-massapproximationissolvedbymeansofthefinite-elementmethod.Theenergylevelsandwavefunctionsofquantum-confinedelectronsandheavyholesareobtainedandshowanagreementwithourprevioustheoreticalandexperimentalstudies.ItisshownintheapproximationofneglectingtheCoulombattractionbetweentheelectronandheavyholethatarelativelylargeStarkshiftofexcitonemissionof4meVisattainablewithanappliedelectricfieldof0.7kV/cm.
简介:InGaAsP/GaAsSCHSQWlaershavebeenpreparedbyLPMOCVD.Thedependenceofthresholdcurrentdensityoncavitylengthwasexplained.Laserdiodesarecharacterizedbytheoutputpowerof1W20W,thresholdcurrentdensity(Jth)of330A/cm^2to450A/cm^2andexternaldifferentialquantumefficiency(ηd)of35%to75%,andthesecharacteristicsareingoodagreementwiththedesignedrequirement.
简介:WhenweuseMOCVDtechnique,anexcellentCdTeepi-layerwasgrownonGaAssubstratesandtheCdTe/GaAshybridsubstratessuitableforgrowingHg1-xCdxTe(CMT)wereobtained.ThexvalueinCMTisbetween0.2and0.8.TheelectricalpropertiesofCMTdependuponthethicknessofCdTeepi-layers.TheCdTe/GaAsinterfacewasexaminedbybothscanningelectronmicroscope(SEM)andelectronaugerspectra(EAS).TheinfluenceofdefectsobservedatinterfaceonelectricalandopticalpropertiesofCMTfihnswasdis-cussed.
简介:Weinvestigatethenonlinearresponseofterahertz(THz)metamaterialperfectabsorbersconsistingofelectricsplitringresonatorsonGaAsintegratedwithapolyimidespacerandgoldgroundplane.Theseperfectabsorbersonbulksemi-insulatingGaAsarecharacterizedusinghigh-fieldTHztime-domainspectroscopy.Theresonancefrequencyredshifts20GHzandtheabsorbanceisreducedby30%astheincidentpeakfieldisincreasedfrom30to300kV/cm.ThenonlinearresponsearisesfromTHzfielddriveninterbandtransitionsandintervalleyscatteringintheGaAs.ToeliminatetheFresnellossesfromtheGaAssubstrate,wedesignandfabricateaflexiblemetamaterialsaturableperfectabsorber.Theabilitytocreatenonlinearabsorbersenablesappealingapplicationssuchasopticallimitingandself-focusing.
简介:利用4.5MeV的氪离子(Kr^17+)辐照(100)晶向本征未掺杂和高掺锌(P型)、(100)和(110)混合晶向的高掺硅(N型)砷化镓(GaAs)半导体材料,辐照注量为1×10^12~3×10^14cm^-2,测试辐照后材料的拉曼光谱。随着辐照注量增大,材料的纵向光学(longitudinaloptical,LO)声子峰向低频方向移动,出现了明显的非对称展宽,并且N型样品辐照后,晶体结构损伤要大于P型与本征未掺杂样品。3种类型样品的LO峰频移随辐照损伤的变化趋势一致,研究表明,掺杂元素不影响材料本身的晶体结构,可能是因为混合晶向的生长方式导致辐照后N型GaAs结构稳定性变差。
简介:Zinchasbeendiffusedinton-typeInxGa1-xAs,InPandGaAsinclosedam-poules,andtheexperimentaldataforInxGa1-xAsrarelyreportedpreviouslyhavebeenob-tained,TheoreticallythelinearrelationsipbetweenlogarithmicdiffusioncoefficientlnDandthecompositionxhasbeendemonstrated,whichisingoodagreementwiththeexperimentalresults.ThecalculateddiffusionjunctiondepthforInGaAsbasedonthediffusionmodelinwhichD^∝c^2isassumedalsoagreeswellwiththatoftheexperment,Finallytheoveralldiffusiontimeinamultiayerheterostructurewasapproximatedast=(∑√-ti)^2.
简介:WefabricatephotoniccrystalslabmicrocavitiesembeddedwithGaAsquantumdotsbyelectronbeamlithographyanddropletepitaxy.ThePurcelleffectofexcitonemissionofthequantumdotsisconfirmedbythemicrophotoluminescencemeasurement.Theresonancewavelengths,widths,andpolarizationareconsistentwithnumericalsimulationresults.
简介:TheeffectsofgrowthtimeonthestructureandmorphologyofcubicGaNnucleationlayersonGaAs(001)substratesbymetalorganicchemicalvapordeposition(MOCVD)havebeeninvestigatedusingasynchrotronX-raydiffraction(XRD).TheXRDresultsshowthattheGaN111reflectionsat54.75°inχareameasurablecomponent,howeverthe002reflectionsparalleltoGaAs(001)surfacearenotdetected.TheXRDΦscansandpolefiguresgiveaconvincingproofthattheGaNnucleationlatyersshowexactlythecubicsymmetricalstructure.Thecoherencelengthsalongtheclose-packed<111>directionestuimatedfromthe111peakarenanometerorderofmagnitude,Theoptimalphotoluminescence(PL)spectrumwasobtainedfromthecubicGaNepilayerdepositedonthenucleationlayerfor60sec.
简介:AseriesofGaAs/AlAsmultiple-quantumwellsdopedwithBeisgrownbymolecularbeamepitaxy.Thephotoluminescencespectraaremeasuredat4,20,40,80,120,and200K,respectively.Therecombinationtransitionemissionofheavy-holeandlight-holefreeexcitonsisclearlyobservedandthetransitionenergiesaremeasuredwithdifferentquantumwellwidths.Inaddition,atheoreticalmodelofexcitonicstatesinthequantumwellsisused,inwhichthesymmetryofthecomponentoftheexcitonwavefunctionrepresentingtherelativemotionisallowedtovarybetweenthetwo-andthreedimensionallimits.Then,withintheeffectivemassandenvelopefunctionapproximation,therecombinationtransitionenergiesoftheheavy-andlight-holeexcitonsinGaAs/AlAsmultiple-quantumwellsarecalculatedeachasafunctionofquantumwellwidthbytheshootingmethodandvariationalprinciplewithtwovariationalparameters.Theresultsshowthattheexcitonsareneither2Dnor3Dlike,butareinbetweenincharacterandthatthetheoreticalcalculationisingoodagreementwiththeexperimentalresults.
简介:在测试了AlGaAs/GaAsHBT(异质结晶体管)的直流特性和S参数的基础上,建立了其微波小信号等效电路,准确的等效电路有利于其微波线性应用的分析.应用Voltera级数,计算了AlGaAs/GaAsHBT放大器的三阶互调失真,计算结果和双音测试结果相当一致,该HBT良好的线性特性证明了其较好的线性应用前景
简介:High-strainInGaAs/GaAsquantumwells(QWs)aregrownbylow-pressuremetal-organicchemicalvapordeposition(LP-MOCVD).Photoluminescence(PL)atroomtemperatureisappliedforevaluationoftheopticalproperty.Theinfluenceofgrowthtemperature,V/IIIratio,andgrowthrateonPLcharacteristicareinvestigated.ItisfoundthatthegrowthtemperatureandV/IIIratiohavestrongeffectsonthepeakwavelengthandPLintensity.Thefull-widthathalf-maximum(FWHM)ofPLpeakincreaseswithhighergrowthrateofInGaAslayer.TheFWHMofthePLpeaklocatedat1039nmis20.1meV,whichgrowsat600°CwithV/IIIratioof42.7andgrowthrateof0.96mm/h.