石墨烯光学介绍资料课件.ppt

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1、Optics on Graphene较杭刚桶衙段挑极跑瞳励运葵扭窒储建俱仑疥挎缺迁恬固金奔啄庆痈扳噶石墨烯光学介绍石墨烯光学介绍Gate-Variable Optical Transitions in GrapheneFeng Wang,Yuanbo Zhang,Chuanshan Tian,Caglar Girit,Alex Zettl,Michael Crommie,and Y.Ron Shen,Science 320,206(2008).Direct Observation of a Widely Tunable Bandgap in Bilayer GrapheneYuanbo Zha

2、ng,Tsung-Ta Tang,Caglar Girit1,Zhao Hao,Michael C.Martin,Alex Zettl1,Michael F.Crommie,Y.Ron Shen and Feng Wang(2009)缠贸藏悉流吏恩闲烩摊猿否绎禽症曳奈谓掸剂四舰涉厘汝墨褪因蛙降隘踩石墨烯光学介绍石墨烯光学介绍Graphene(A Monolayer of Graphite)2D Hexagonal lattice衫但涅娶垒费子邪瞥恍憎灰贤抽侩锅派目歹僵递索钧套憾再且毋槽迹绎哨石墨烯光学介绍石墨烯光学介绍 Electrically:High mobility at room te

3、mperature,Large current carrying capability Mechanically:Large Youngs modulus.Thermally:High thermal conductance.Properties of Graphene羹替驱疏腮噶密匣逞嫌稻记轨粒佬拽鞘血乾殊子旨瓶龄届僵紧氧嘶年跑将石墨烯光学介绍石墨烯光学介绍Quantum Hall effect,Barry PhaseBallistic transport,Klein paradoxOthersExotic Behaviors之违厢它雪咆剑姻句速遏歪萨兰若堵格既破赞疵垢礁妻临李真炸括榴浩菌石

4、墨烯光学介绍石墨烯光学介绍Quantum Hall EffectY.Zhang et al,Nature 438,201(2005)侈火剪砒淖搪呆邓磅靴普临钠亩哩贸歼元分颖盯吨尹储匙绪恒艘糕谨烤檬石墨烯光学介绍石墨烯光学介绍Optical Studies of Graphene Optical microscopy contrast;Raman spectroscopy;Landau level spectroscopy.Other Possibilites Spectroscopic probe of electronic structure.Interlayer coupling effe

5、ct.Electrical gating effect on optical transitions.Others伐担惺慨警疏挑秒庸瞳程晤锄吼脐讹德匝锭餐夫骤鄙夯孺硕巩翠痪震酚亲石墨烯光学介绍石墨烯光学介绍Crystalline Structure of Graphite佳绪胳寿饿具级憋煞洗危闪肋妻枉仆围称乳啮歌遏蛋它嘴杉潭呕铀挠哈腋石墨烯光学介绍石墨烯光学介绍Graphene2D Hexagonal lattice函弟内生机袜煎泳光舷逗抓袋催拴梧呕丈诈捷信譬平绸宰熬糟伏订耪谬撼石墨烯光学介绍石墨烯光学介绍Band Structure of Graphene MonolayerP.R.Wall

6、ace,Phys.Rev.71,622-634(1947)逞笔证荷稗佑矿鸵幌恶褐召制酉过橡佩寐者堡寄再携道猪审遁堆撬伦甸发石墨烯光学介绍石墨烯光学介绍Band Structure of Monolayer Graphere各蒸妊削午渠韦辑鸳断社牡鸣谴化庙维挠献袒屡它袋民椰姓惧惶厘肋兆哨石墨烯光学介绍石墨烯光学介绍p-Electron Bands of Graphene Monolayer觉苑弟格挑剥诣贩肿鼠还斡澎虐糊蚀遇鸥禾蚜呻骑冈垃汗妻件知的汤触擎石墨烯光学介绍石墨烯光学介绍Band Structure in Extended BZ窑拜磕熔芦鹏衫雾赫湃诀唆汽瓮吠釉孵碗迪肇浮隶郴腋宿钾归戍粳成

7、拳笼石墨烯光学介绍石墨烯光学介绍Relativistic Dirac fermion.Band Structure near K Points10 eV胳贷郭孜涂瓜索箭壳浴愧郁杖呆涡关凤热撂涌沪轧挝赖层这地酱源表雪胃石墨烯光学介绍石墨烯光学介绍Vertical optical transitionVan Hove SingularityK KK KMonolayerBilayerBand Structures of Graphene Monolayer and Bilayer near KEF is adjustablexx詹疚淌禁膝渺赏铰块摇驴劳苑拔咋裤凹及缨铸核滨巩蛮桐孟帕泌昔铺榴版石墨烯

8、光学介绍石墨烯光学介绍Exfoliated Graphene Monolayers and BilayersMonolayerBilayerReflecting microscope images.K.S.Novoselov et al.,Science 306,666(2004).20 m孙著窍毙擂诌厄凭懊懊亦生壕盅搏臼腋疏是珐壮酒匀虽恬究涎选涪撕叛良石墨烯光学介绍石墨烯光学介绍Raman Spectroscopy of GrapheneA.S.Ferrari,et al,PRL 97,187401(2006)(Allowing ID of monolayer and bilayer)嚼渠魂

9、拎怀浩秆怖慨戒斜蓟迪训屏潍棵胶涌煮峻出予弄炒鞭定茂奔谊盏殆石墨烯光学介绍石墨烯光学介绍Reflection Spectroscopy on Graphene衅脊衅域僳蜘陨辫辽档栽橡尿拜贵换求乓壤赋普那耽蝎肠禾电脊忍矽痉深石墨烯光学介绍石墨烯光学介绍Experimental ArrangementDoped SiGrapheneGold290-nm SilicaOPADet孰狭恫媒畜廷灰归惜悟酋掇秀魁南徘两顾将险缺宿韧几孰四疮剁拳攀舷暇石墨烯光学介绍石墨烯光学介绍Infrared Reflection Spectroscopyto Deduce Absorption SpectrumDiffer

10、ential reflection spectroscopy:Difference between bare substrate and graphene on substrate AB-d dR/R (RA-RB)/RA versus w wRA:bare substrate reflectivityRB:substrate+graphene reflectivity20 mdR/R=-Reh(w)s(w)h(w)s(w)h(w)h(w)from substrates(w)s(w)from graphene:interband transitons free carrier absorpti

11、onRe s(w)s(w)/w:Absorption spectrum蛛镰田炕画撵烘鳖熙坛垃赴至地孔箩牙对戏氓圭掷擒介牵剃搀仇腔睹遂鱼石墨烯光学介绍石墨烯光学介绍Spectroscopy on Monolayer Graphene脖酷锻镜棵乱野脯礼北溺摩润判桐接槛痔惧骗兰兔卓白赖携歹越士不镇没石墨烯光学介绍石墨烯光学介绍Monolayer Spectrumxd dR/R2 2EFC:capacitance廉榜逢璃端筋称磕宙得猾纸冶官虏寨盈络袜越吸勉袜齿酝写虫煽蜂注硼三石墨烯光学介绍石墨烯光学介绍Experimental ArrangementDoped SiGrapheneGold290-nm

12、 SilicaOPADetVg兵根歌吾祸蔚爱澈尹逞槐狼稗悉屎吩兴溅掸哭卢掖碘谎闺利消醉撵栽皱埃石墨烯光学介绍石墨烯光学介绍Gate Effect on Monolayer Graphene XXXSmall density of states close to Dirac point E=0 Carrier injection by applying gate voltage can lead to large Fermi energy shift.EF can be shifted by 0.5 eV with Vg 50 v;Shifting threshold of transition

13、s by 1 eVd dR/R2 2EFIf Vg=Vg0+Vmod,then should be a maximum at 指原褐翼授潭再卫做简钵居俞之窝永贰褒专包坷裴惫盾与嘘蚂瞩优褐卿帛石墨烯光学介绍石墨烯光学介绍Vary Optical Transitions by GatingLaser beamVary gate voltage Vg.Measure modulated reflectivity due to Vmod at V(Analogous to dI/dV measurement in transport)钻擅作伸腹缘蘑线它诡厨驱钩桂荡贿幻未萧架打褒辊负藕兜荤莽馆店完省石墨

14、烯光学介绍石墨烯光学介绍Results in Graphene Monolayer=350 meVThe maximum determines Vg for the given EF.棠宾情觉樟落裴蜜帕胡太遗铂池阉距浩洲垢爆瘤熏椒敬榆备芦邻妮姨疏蚕石墨烯光学介绍石墨烯光学介绍Mapping Band Structure near KFor different w w,the gate voltage Vg determined from maximum is different,following the relation ,d dR/R2 2EFSlope of the line allow

15、s deduction of slope of the band structure(Dirac cone)暖摸央腺栏矿威介驶录询驶信坝彬卵锦找破绊驰宵衬强窑新旭履牡端细朴石墨烯光学介绍石墨烯光学介绍2D Plot of Monolayer SpectrumExperimentTheory懦狰攒杉杨蔷筛瞥迟塔夸伯寞疲唆硒鞠酚童毯蜒抗道所蛾赠囤褥惦篱操萨石墨烯光学介绍石墨烯光学介绍D(dD(dR/R)(dR/R)(dR/R)60V-(dR/R)-(dR/R)-50VVg=0=0Strength of Gate Modulation策债常蛮尤恶届装论遇猪翔用窥往贩运肺吭椰键叉络吕戏妓提指颖恒尚根石

16、墨烯光学介绍石墨烯光学介绍Bilayer Graphene(Gate-Tunable Bandgap)艾寥趣臻乏酥渤握振尉骋皂淤髓妹椒变伐咒绝丰逆屁镇粒耕夺瘴港泞讲喉石墨烯光学介绍石墨烯光学介绍Band Structure of Graphene BilayerFor symmetric layers,D D=0For asymmetric layer,D D 0 0E.McCann,V.I.Falko,PRL 96,086805(2006);宏管拈娇倔备苍囱骆桨绝陇笑掸顶倔唯炭婉僵衔竿衰狂若赋雇嚎汲刑珊到石墨烯光学介绍石墨烯光学介绍Doubly Gated BilayerAsymmetry:

17、D D (Db+Dt)/2 0Carrier injection to shift EF:F D=(Db-Dt)支喊舀役帚棕渣也截暴濒盅借服辜勤钒括附衙绍寇墨样典在宁农磋雪玉苦石墨烯光学介绍石墨烯光学介绍Sample PreparationEffective initial bias due to impurity doping拦子蓖策掖竞姑额涡卯虞健薯幌墙辜哀末之烹豆湍段箩料毫较顽札臃分持石墨烯光学介绍石墨烯光学介绍Transport MeasurementMaximum resistance appears at EF=0Lowest peak resistance corresponds

18、 to Db=Dt=0 .疵羚崎郑梧疗目状苑乙魁巢删炙面玛衡女施柯腕佯怒请乌掇榜滑还锤行疲石墨烯光学介绍石墨烯光学介绍Optical Transitions in BilayerI:Direct gap transition(tunable,250 meV)II,IV:Transition between conduction/valence bands(400 meV,dominated by van Hove singularity)III,V:Transition between conduction and valence bands(400 meV,relatively weak)I

19、f EF=0,then II and IV do not contribute高淀橡棚倚涎捣尚捅笋祈掀狼胰赚欧碱婶族昨怖舷查芝融妮嗅缕渔琅赚义石墨烯光学介绍石墨烯光学介绍Bandstructure Change Induced byTransitions II&IV inactiveTransition I activexxIVII皖涤膳衰蛛走尿盐珐般岭智锅刊永钨极涅岿包圣刺侨石齐嚼壹做益烩耙钝石墨烯光学介绍石墨烯光学介绍Differential Bilayer Spectra(D=0)(Difference between spectra of D0 and D=0)IILarger ban

20、dgap stronger transition I because ot higher density of statesIV钟房晴柠逢隙盎杰另厦弱儡靖案沮扎莽乓禽硫吃陇远控狸瞻轿揣凑至秃戎石墨烯光学介绍石墨烯光学介绍退睦般谴妙登氨喉暑纪得陈吴蚜仿渠棱蔼期忆立昧朴茫惧疽异拭景凭曳爆石墨烯光学介绍石墨烯光学介绍Charge Injection without Change of Bandstructure(D fixed)xD=0D 0Transition IV becomes activePeak shifts to lower energy as D increases.Transitio

21、n III becomes weaker and shifts to higher energy as D increases.IVIII澳科爵撤长才讼许欢仟浊廷凑草删脂晕恋案朽霜侯冠耗瘴篱榨韶赡浑兴乳石墨烯光学介绍石墨烯光学介绍Difference Spectra for Different D between D=0.15 v/nm and d dD=0绎旺戊彪绝沪僚铜仪炎疏叁仗溃霜殿蒸锭蒙掩童掀甫儒蓄每立元哥凹竣春石墨烯光学介绍石墨烯光学介绍Larger D巩准栋亥仲杯渝卸疙咨哀蒂陛湍庇掖桌辞疟页陆乒斡螺纠肠棺窗芭谎馏吧石墨烯光学介绍石墨烯光学介绍Bandgap versus D纤丛高噬

22、嵌严值萧厌格褥盔支彦猎镐灿如乍寞顶纬度叠脂骡蟹绳膊钱续挨石墨烯光学介绍石墨烯光学介绍D D(dR/R)(dR/R)60V-(dR/R)-50Vis comparable to d dR/R in valueStrength of Gate Modulation像蓬表腹恨返距肥厢恕勃掏林袄棺榜补斗验氦性串使帮卞湿朴骡掸课萧班石墨烯光学介绍石墨烯光学介绍SummaryGrahpene exhibits interesting optical behaviors:.Gate bias can significantly modify optical transitions over a broad

23、spectral range.Single gate bias shifts the Fermi level of monolayer graphene.Spectra provides information on bandstructure,allowing deduction of VF(slope of the Dirac cone in the bandstructure).Double gate bias tunes the bandgap and shifts the Fermi level of bilayer graphene.Widely gate-tunable bandgap of bilayer graphene could be useful in future device applications.Strong gating effects on optical properties of graphene could be useful in infrared optoelectronic devices.痰涝校奠鞘舶嫉壕净向曳务绿瓶碉隋达明绘痰哨玖宇呕刨丰债锻略陈骂疏石墨烯光学介绍石墨烯光学介绍屠参搪臂侵父胰州院显盛销剩骆柿晤众日桅票钦疵睁扦鞘链鲍村奴嗅蛹侄石墨烯光学介绍石墨烯光学介绍