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1、光电子学期末复习资料h = 6.63 x 10-34 JskB =1.38 x 10-23 J / Km = 9.1x 10-31 kge = 1.6 x 10-19 C绪论1、光电子器件有哪些功能；Information generation, Information transfer, Information enhancement/amplification, Information manipulation, Information reception/detection, Information display2、有用的光电子器件应该拥有的特性；High gain, Non-line
2、ar response, Input/output isolation, Tuability, High speed, Low power consumption, High power output, High temperature3、电子器件和光电子器件的优缺点对比；Electronic devices:a. metallic inter-connects limit the inter-connectivity of the devices;b. difficult to transmit information over very long distances;c. external
3、 electromagnetic interference (EMI) effects;d. charged particles scattering processOptoelectronic devices:a. Immunity to electromagneticb. Non-interference of two or more crossed beamsc. High parallelismd. High speed-high bandwidthe. special function devicef. wave nature of light for special devices
4、g. Nonlinear materialsh. Photonics-electronics coupling4、光电子器件的应用范围；a. Optical communications: Cable TV Longhaul communication, LAN communicationb. Data communication: Equipment control, Local area network, Factory automationc. Defense applications: Laser guided systems, Radard. Consumer electronics
5、 product: Compact disc, Laser printer, Night vision, thermal imaging, Video disc libraries 5、三个窗口波长；850nm, 1310nm, 1550nm6、光电子器件的发展趋势；WDM OEICTrend:a. high response speedb. wavelength division multiplexing technology (WDM)c. function devices: optical fiber LD , optical fiber amplifierd. optoelectron
6、ic integrated technology (OEIC)第一章1、光电子器件的工作机理，基于光和电磁场的相互作用；Optoelectronic device depends on the interactions of photons or electromagnetic field with semiconductors.Interaction: photon - semiconductorElectromagnetic Field - semiconductor2、光在半导体中的传播规律：按指数规律衰减；I (z) = I (0)e -s3、折射率实部、虚部；The real par
7、t of index = speed of lightThe imaginary of index attenuation of light光的吸收和光的发射(画示意图);4、受激辐射和自发辐射比较；The stimulated emission is due to the initial photons present in the system and the emitted photons maintain phase coherent with the initial photons.The spontaneous emission comes from the perturbatio
8、ns and the emitted photons are incoherent with no phase relationship.5、直接带间跃迁和间接带间跃迁的物理图像、特点、吸收系数；特点： Vertical in k-space吸收系数:1.4 Direct Interband TransitionsA schematic of direct interband transitionsa = A(hO E )1/2 , A is a constant特点：(1) Not vertical in k-space(2) Mediated by a phonon interaction
9、 or other scattering process(3) Second order process吸收系数：a = K。+ yr顺-E?2K0 is a constant Kg ) is a temperature dependent factor7、辐射的种类：辐射复合和非辐射复合，俄歇复合的两面性；Non-Radiative RecombinationNo emitting photonsRadiative Recombinationemitting photons俄歇复合的两面性：(1) Auger processes are unimportant in semiconducto
10、rs with bandgaps larger than 1.5eV(2) They become quite important in narrow bandgap materials and are thus a serious hindrance for the development of long wavelength lasers.(3) Auger processes could be mediated by defects. Deep levels in the bandgap can be involved in the Auger processes.(4) For hig
11、h quality materials, these defect assisted processes are not important.8、粒子束反转时的自发辐射率;R = spon4l4t009、增益与费米分布函数之间的关系；g h )泛fe (Ee ) - (1 - fh (Eh)10、俘获时间：CCHC、CCHS；1T PnrNO thb p匚 _1nr N U b ，t th n11、CCHC的全称及示意图，并说明过程;全称：CCHCConduction(electron) - Conduction(electron) - heavy hole - Conduction(elec
12、tron)Initial state: 2 electrons+1 holeFinal state: hot electronAfter the scattering, an e-h pair is lost and one is left with a hot electron.The hot electron subsequently loses its excess energy by emitting phonons.12、俄歇复合率与n之间的关系，俄歇复合率的计算及影响俄歇复合率的因素：带隙、温度等；R = FnAuger带隙增加，俄歇复合率下降；温度升高，俄歇复合率上升。13、扩散
13、长度的理解及计算；The average distance of a hole(electron) can move before recombinationLp = Dp p，Ln = h = E类型：1. Direct Absorption 直接吸收、3 2吸收系数：aX106 m尝立尝彖（m J夫夫x ，力方（与吸收光子能量有关）2. Indirect Absorption 间接吸收吸收系数：an（必）=K+k（t）（必-Eg）E / 截止频率(cutoff frequency):u = gh截止波长(cutoff wavelength):. hc 1.24 /、人=(pm)c E E
14、(eV)4、分析本征吸收的吸收图谱的变化规律(图2.3的Si和GaAs吸收系数曲线)；Si、Ge: weak absorption at the bandedge(indirect absorption )GaAs: strong absorption at the bandedge(direct absorption )5、例题2.2；A Ge detector is to be used for an optical communication system using a GaAs laser with emission energy of 1.43 eV.Calculate the d
15、epth of the detector needed to be able to absorb 90% of the optical signal entering the detector.Condition: Ge detector a = 2.5 x 104 cm tGaAs laser力s = 1. 4 eVCalculation: the depth of Ge for 90% optical signal be absorbedSolution: To absorb 90% of the optical signalP_ = 1 - 90% = 10%Pop (0)n e-aL
16、= 10%n L = - 1 ln0.1 = 0.92ma6、非本征吸收的类型；1) . Impurity Absorption (杂质吸收)2) . Intraband Absorption 滞内吸收)3) . Exciton Absorption (激 子吸收)7、长波长检测的方法；Long wavelength detector (长波长检测器)(1) Intrinsic detector :a very narrow bandgapdifficult to fabricate high quality devices(2) Extrinsic detector:thick Sample
17、Operated at low T8、产生率、响应度、量子效率的含义及其计算；例题2.3；1) . Rate of e-h pair generation G lG l is the carrier generation per unit volume per second :G =以P=aJ (x)L phnJ h(x) is the photon flux density impinging at point x2) . Responsivity (响应度)The ratio of the photocurrent to the optical power impinging upon t
18、he semiconductor.JL p Rph = Popelectric field TPhoton( E ) n e h pairphotocurrent I l Photocurrent density J l3) . Quantum efficiency (量子效率)门 is the ratio between the carriers collected and photons impinging on the detector.The number of collected carriers门 = Q The number of impinging photonsph eThe
19、 quantum efficiency essentially tells us how many carriers are collected for each photon impinging on the detector.9、PN二极管光电流的组成、特点和计算；（填空）I = I +1 +1 = eG （L + L + W）AL nL pL L1L p nI l : electron diffusion current in the neutral P-region within a distance LnI l : hole diffusion current in the neut
20、ral n-region within a distance LpIl1： drift current in depletion regionIL1I l and I l : diffusion current under almost no electric fields, slow time response drift current under high electric fields, very fast time response 10、PN结的应用方式；（光伏、光电导）;Photovoltaic modePhotoconductive mode11、光电池开路电压、短路电流、转换
21、效率、最大功率输出点的电压和电流；例题2.6；开路电压 the open circuit voltage:VocmkT ilne短路电流 the short circuit current:转换效率 The conversion efficiencyPmax X100% =PinI Vm m X100%Pin填充因子 Fill factor F = m mfIVFfJVoc!Vm FrVOCsc12、非晶硅太阳电池的优点；E 1.6eV n门high absorption coefficient of a-Si n L R measy to fabricate n low price13、光电
22、导检测器的工作原理及特征参量的计算（光电导、器件增益）；Illumination upon the surface （intrinsic） n Excess e-h pair, excess photoconductivity n The charge is detectedPhotoconductivity 佻电导率）：Aa = e5 p （口 + 日）The gain of the photoconductive detector G J增益）:Gphi tG hShows the charges collected by the contact when a e-h pair is ge
23、nerated by absorption14、PIN管的结构、工作原理、光电流、检测效率，PIN管设计需要考虑的因素（P95）；Under illuminationUnder reverse biasedPhotocarriers （光生载流于）are generatedare drifted （漂移）and collected Photocurrent is generated【l = Aef w G （x）dx = AeJ . （0） 1 - e-网一 PhotocarriersAttention: Iis the drift current in the i region, not i
24、ncluding the diffusion current inP + and N + regionThe diffusion current can be neglectedIf R is the reflectivity （反射率）of the surface, I= （1- R）AeJ 方（0）G - e-cwDetector efficiencyThe detector efficiency is the ratio of the density of collected carriers to the incident flux density:门= = （1- R） 1 e-cw
25、Jph （0）The important issues in device design are: 1. Minimizing surface reflection:anti-reflective coatings 2. Maximizing the absorption in the depletion region:metal mirrors nOptical interaction length （光作用长度）I 3. Minimizing carrier recombination:high purity material n t 4. Minimizing transit time:
26、WI n devicespee 5. Minimizing diode capacitance:方;A，（W f）There is a clear tradeoff （折衷）for length W15、PIN管3dB频率与量子效率之间的折衷;2.4 0.4V3dB2兀 tW Lq门七、=（1-R） 1 - e -awAJ（ 人）（0）Lf fn W l而门Tn W个，3dbThere is a clear tradeoff （折衷）for length W between quantum efficiency and speed.A reasonable compromise between
27、 门 and f is to have W between /aand 2a16、APD的结构、工作原理、倍增因子的计算；Reach through APD （RAPD,拉通型 APD）: n + P 兀一P+Microcosmic process:Illumination n photon absorbed n photocarriers at high reverse electric field_hot carriersImpact the electrons in valance band Tmultiply carriers n Photocurrent is generatedMu
28、ltiplication factor Me （倍增因子）a /P1 imp impvmp/Pmp - 11 exp Pimp 1 P WV imp ）imp avlWhen 匕邓 mp，Me -兀 Wimp avlWhen 亦 0,M/ eimWavl17、影响APD带宽的因素（105三个时间）;1） the transit time across the absorbing region （电子穿越光吸收区的渡越时间）t （e）=Wabs七（e）2） the time required for the avalanche process to develop （雪崩过程发生的时间）,_ M
29、 W广成3) the transit time for the holes generated during the avalanche process to transmit through the absorbing region back to the p-region,(雪崩过程中产生的空穴穿越吸收区)t (h)一吃如tr, (h)The overall device response time is thenT. R + MW + R + hu (e)u (h)bandwidth 次 t t18、几种先进结构检测器的特点；Important issues in detectors :
30、Tunability 可调性E 一人Speed 响应速度t,(T f个Integration可集成化第三章：1、发光过程三步，三个效率对应三个过程；2、LED的偏置状态；3、LED材料的选择；4、三个效率的计算，分别提高各效率的方法；5、计算反射系数、最大接收角和与光纤的耦合效率；6、各种先进LED的特点：异质结、边发射、面发射；7、P-I特性曲线；8、线宽（计算）：低注入和高注入；9、温度特性；10、如何提高LED的输出功率和调制带宽；11、三种失效类型及特点；参考：一、1、发光过程三步，三个效率对应三个过程；四、三个效率的计算，分别提高各效率的方法；五、计算反射系数、最大接收角和与光纤的耦
31、合效率；The major optoelectronic process in LED:1、The minority carriers injected in P-N junction（ under electric fields）Injection efficiency （注入效率）Y 二Jw-L-奶 j + j + j j + jhigh quality =trap center JGR 1J. IFor HMJ (homojunction):P layer is designed to be emitting region =y网 TFor HTJ (heterojunction)2、R
32、ecombination between minority carriers injected and majority carriersRadiative efficiency (辐射效率)Given：N I,BRn = r Qr R + RR = W个 n n =一1一 IrQrT1+fTnr1T=1 1+T Tr nr1=HTnr3、Radiation 门=y 门.门灯 inj Qr opt%The methods to increase 咿:1) To minimize the absorption loss:absorption coefficient a J indirect ga
33、p materials(bad choice)absorption layer thickness w J emitted near the surfacebut surface recombination =/. . IinjEffective method : Compound alloys z change Eg Tfrom absorption region to emitting surface2) to maximize surface transmissionReflection coefficient R (反射系数)f VR =li (called the Fresnel l
34、oss)i nr2 +nrl)By Dielectric Encapsulation3) To avoid total internal reflection (全反射)(if emitted to the air )nr2 Drl3Z : Critical angle for total internal reflectionFor GaAsP s = 3.6 M 0 = 16.2。二 % 4%Here, TIR is an issue, while TIR is utilized in the fiber.Once again, use of the encapsulation suppr
35、esses this loss.4) Maximize the efficiency coupled into the fiber(if emitted to the fiber)The maximum angle for acceptance0A= sin1 (%，-循产=血一(4) Ls JAn is called the numerical aperture径)of the fiberThe fraction if the light coupled into the fiber:二、LED的偏置状态；Working state of LED forward biased三、LED材料的
36、选择；Only Direct bandgap semiconductors are suitable for LEDSubstrate availability: epitaxial crystal growth techniques (晶体外延生长工艺) lattice matchingGaAs , InP used for substrate六、各种先进LED的特点：异质结、边发射、面发射；1、Heterojunction LEDEmitted photons reabsorbed can be avoid byinjecting charge from a larger bandgap
37、material into a narrow gap active region .HT LED made by epitaxial technology2、Surface emitting LEDEmitting light is coupled into the fiber directly etching a hole in the LED and attaching the fiber by epoxy resin (环 氧树脂)Horizontal and Vertical diffuse angles both are 120，So the efficiency coupled i
38、nto the fiber is low.3、Edge emitting LEDAn important ingredient of the edge emitting LEDconfine theelectronsand holesto the active layerthe wide gap cladding layerscause the emitted photons to travel along the LED axis and emerge from the edge of the device.Horizontal diffuse angle is 120 Vertical d
39、iffuse angle is 30The efficiency coupled into the fiber is high七、p-i特性曲线；Saturation due to heating effectsForward Current p I linear relationship ( small I); P starts to saturate (large I).八、线宽（计算）：低注入和高注入;AE kTat low injectionAE gkTat high injectionN匚：the effective density of states九、温度特性；The tempe
40、rature of the diode influences the e-h recombination efficiency through two phenomenon: i) Leakage of injected carriers into the contact regions at high temperatures;Low temperature low leakage currentHigh Temperaturek injected change is spread out in energy higher leakage currentii) Auger processes
41、 that contribute to non-radiative recombination.D-E /(k3T)RAugerLow Temperature:Auger recombination can be ignoreHigh Temperature:Auger recombination cannot be ignoreTemperature rise can induce the output power decrease.Experience equation :IPh = IPh (0) exp十、如何提高LED的输出功率和调制带宽; T f hvndA p = Ip/u =
42、To increase the optical power of the device, one has the following design considerations:i) Injected carrier density n - 12nsii) Device areafabrication technology =Aiii) Active region thicknessd 个二尹 T;d Tn f Jtradeoff between high output power and modulation bandwidth十一、三种失效类型及特点；I. Infant failures
43、(早期失效)； Occur due to fabrication defects;Can be screened out during the bum-in period of 100 hour operation; To avoid it by high quality substrate and advanced fabrication technologyII. Freakfailures (反常失效)： Occur due to extreme combinations of the random defects; Occur after burn-in, but long befor
44、e the expected lifetime.III. Gradual failures (渐变失效)：Failures involving gradual degradation of output powerMTTF (mean time to failure) PQ)= B,20%第四章:1、2、LED和LD的区别：LD: Stimulated EmissionLED： Spontaneous Emission光波限制因子的含义：The active region in which e-h pairs are recombining may only occupy a small fraction of the optical cavity.=LJ | F （z） |2 dx纵模间频率间隔与能量间隔:
