conductors insulators and semiconductors

... Inc. 3 StimulatedEmissionandOptical GaininSemiconductors Thischapterpresentsthebasictheoryandcharacteristicsofstimulated emissionandopticalamplificationgaininsemiconductors.Theformeristhe mostimportantprinciplethatenablessemiconductorlaserstobeimplemented, andthelatteristhemostimportantparameterforanalysisofthelaser performances.First,stimulatedemissioninsemiconductorsisexplained ,and thenquantumtheoryanalysisandstatisticanalysisusingthedensitymatrix oftheopticalamplificationgainaregiven.Stimulatedemissionandoptical gaininsemiconductorquantumwellstructureswillbepresentedinthenext chapter. 3.1BANDSTRUCTUREOFSEMICONDUCTORSAND STIMULATEDEMISSION 3.1.1BandStructureofDirect-TransitionBandgap Semiconductors Semiconductorlasersutilizetheinterbandopticaltransitionsofcarriersina semiconductorhavingadirect-transitionbandgap.Asiswellknowninthe electrontheoryofsolids[1],thewavefunctionofanelectronofwavevector k(momentumhh k )inanidealsemiconductorcrystalcanbewrittenasa Blochfunction j ... Dekker, Inc. 3 StimulatedEmissionandOptical GaininSemiconductors Thischapterpresentsthebasictheoryandcharacteristicsofstimulated emissionandopticalamplificationgaininsemiconductors.Theformeristhe mostimportantprinciplethatenablessemiconductorlaserstobeimplemented, andthelatteristhemostimportantparameterforanalysisofthelaser performances.First,stimulatedemissioninsemiconductorsisexplained ,and thenquantumtheoryanalysisandstatisticanalysisusingthedensitymatrix oftheopticalamplificationgainaregiven.Stimulatedemissionandoptical gaininsemiconductorquantumwellstructureswillbepresentedinthenext chapter. 3.1BANDSTRUCTUREOFSEMICONDUCTORSAND STIMULATEDEMISSION 3.1.1BandStructureofDirect-TransitionBandgap Semiconductors Semiconductorlasersutilizetheinterbandopticaltransitionsofcarriersina semiconductorhavingadirect-transitionbandgap.Asiswellknowninthe electrontheoryofsolids[1],thewavefunctionofanelectronofwavevector k(momentumhh k )inanidealsemiconductorcrystalcanbewrittenasa Blochfunction j ... Inc. ThematrixelementjMj 2 forthetransitionswherewavevectorconservation doesnotnecessarilyholdisgivenbytheproductofEq.(3.29)andEq.(3.34). Equation(3.34)indicatesthatjMj 2 islargeintheregionofkwherea 2 k 2 issmall. AlthoughEq.(3.34)iseffectivefortransitionsbetweenthebandtail andaextendedband,itdoesnotapplyfortransitionsbetweenparabolic bandswithlargerenergiesandthosebetweenbandtails.Tosolvethe difficulty,Sternexpressedeachconduction-bandelectronandeachvalence- bandelectronintheformofEqs.(3.30 )and( 3.31).Thevaluesofawere determinedbyfittingtheeffectiveenergyreductionduetothelocalizationto theeffectiveenergyreductioncalculatedfromthedensityofstatesinthe GHLBTmodel.ThevalueofjM env j 2 wascalculatedbyusingthesevaluesin Eq.(3.33)andaveragingoverallkdirectionsandthelocalizationsitesr i [11].Theresultiswrittenas jM env j 2 ¼ 64pb 3 ðt 4 Àq 4 Þ À5 ½ðb 4 À5b 2 B 2 þ5B 4 Þð3t 4 þq 4 Þðt 4 Àq 4 Þ 2 þ8b 2 B 2 t 2 ð3b 2 À10B 2 Þðt 8 Àq 8 Þ þ16b 4 B 4 ð5t 8 þ10t 4 q 4 þq 8 Þð3:35Þ B 2 ¼ 1 a c a v ;b¼ 1 a c þ 1 a v ;t 2 ¼b 2 þk 2 c þk 2 v ;q 2 ¼2k c k v wherek c andk v arethewavenumbersofvalence-bandandconduction- bandelectronswiththeeffectiveenergyreductiontakenintoaccount.The matrixelementjMj 2 ¼jM(E 1 ,E 2 )j 2 ¼jM B j 2 jM env j 2 usingthisjM env j 2 is calledtheSternenergy-dependentmatrixelement(SME). Figure3.6showsanexampleofjM env j 2 calculated...

Ngày tải lên: 23/10/2013, 20:15

... tsnl Synthesis and Application of Nanosize Semiconductors for Photoxidation of Toxic Organic Chemicals J.P. Wilcoxon, Nanostructures and Advanced Materials Chemistry Sandia National Laboratories Albuquerque, ... Photooxidation) •Photocatalysis using UV light and nanosize TiO 2 and SnO 2 . •Photocatalysis using visible light and MoS 2 nanoclusters.  Acknowledgement: Div. Of Materials Science and Engineering, Office of Science, ... Science/Environmental Research (ER/ES) Program. tsnl Light Absorbance and Redox Potentials- -1.0 0.0 1.0 2.0 3.0 Redox Potentials of Various Semiconductors at pH 7 Potental vs. NHE H 2 O/OH . potential TiO 2 MoS 2 (bulk) MoS 2 (d=4.5...

Ngày tải lên: 14/03/2014, 20:20

... twentieth century. Semiconductors for Micro and Nanotechnology— An Introduction for Engineers Jan G. Korvink and Andreas Greiner Crystal Structure Semiconductors for Micro and Nanosystem Technology ... Definitions and Acronyms Semiconductors for Micro and Nanosystem Technology 19 1.2 Popular Definitions and Acronyms The microelectronic and microsystem world is replete with terminology and acronyms. ... almost have metal-like SiO 2 Semiconductors for Micro and Nanotechnology— An Introduction for Engineers Observed Lattice Property Data Semiconductors for Micro and Nanosystem Technology 35 Silicon...

Ngày tải lên: 17/03/2014, 14:59

... (54) \Ga:As t e+ k 'Ga-As 16 Electrochemistry of Semiconductors and Electronics 4.0 COMPOUND SEMICONDUCTORS Compound semiconductors can be chosen to match their optoelectronic properties ... difference in the dissolution behavior of metals and semiconductors lies in the concentration and type of charges responsible for surface reactions. In semiconductors, the concentration of charge carriers ... involving semiconductors and/ or electronics mentioned in this publication should satisfy himself as to such suitability, and that he can meet all applicable safety and health standards. We...

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Ngày tải lên: 13/05/2014, 09:08

... band and the bottom of the conduction band there is an energy gap, later called the bandgap (see Chap. 6). Fig. 2.5. Schematic of the origin of valence and conduction band from the atomic s and ... bonding and (b,d) antibinding sym- metric (a,b) and nonsymmetric (c,d)sp 3 orbitals 2.2.3 sp 2 Bond Organic semiconductors (see Chap. 16) are made up from carbon compounds. While for inorganic semiconductors ... OpticalProperties 353 14.4 Piezoelectricity 353 15 Magnetic Semiconductors 359 15.1 Introduction 359 15.2 Magnetic Semiconductors 359 15.3 Diluted Magnetic Semiconductors 361 15.4 Spintronics 365 15.4.1 SpinTransistor...

Ngày tải lên: 04/06/2014, 14:33

... Conductive Zinc Oxide Basics and Applications in Thin Film Solar Cells Editors: K. Ellmer, A. Klein, and B. Rech 105 Dilute III-V Nitride Semiconductors and Material Systems Physics and Technology Editor:A.Erol 106 ... Depla and S. Mahieu 110 The Physics of Organic Superconductors and Conductors Editor:A.Lebed 111 Molecular Catalysts for Energy Conversion Editors: T. Okada and M. Kaneko 112 Atomistic and Continuum ... Heywang, K. Lubitz, andW.Wersing 115 Lithium Niobate Defects, Photorefraction and Ferroelectric Switching ByT.VolkandM.W ¨ ohlecke 116 Einstein Relation in Compound Semiconductors and Their Nanostructures By...

Ngày tải lên: 04/06/2014, 14:44

... larger in size and thus ‘closer’ to bulk form than the 46.3-nm film. Also, Figures 9 and 10 show bulk and thin film values of γ as a function of temperature. By comparing Figures 9a and 10a, it ... increases. To help understand these relationships, a model is presented, and equations are obtained to help understand the mechanisms responsible for these properties and to give insight into ... J: Handbook of Modern Sensors: Physics, Designs, and Applications. New York: Springer-Verlag; 2004. 25. Lacy F: Evaluating the resistivity-temperature relationship for RTDs and other conductors. ...

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... will Ⅲ Understand the embedded Linux development environment. Ⅲ Understand and create Linux BSP for a hardware platform. Ⅲ Understand the Linux model for embedded storage and write drivers and applications ... leaks and memory corruption in applica- tions and drivers. Ⅲ Learn methods to profile applications and the kernel. Ⅲ Understand uCLinux architecture and its programming model. Ⅲ Understand the ... I2C subsystem, and USB gadgets. vi Embedded Linux System Design and Development Ⅲ Borland is a registered trademark of Borland Software Corporation in the United States and other countries. ...

Ngày tải lên: 04/08/2012, 14:23

... during transport and handling – particle and ingredient segregation (separation) occurs when particles of different sizes and bulk densities are blended together and transported or handled. 4. ... Size, Bulk Density and pH Particle size and particle size uniformity of feed ingredients are important considerations of livestock and poultry nutritionists when selecting sources and determining ... of U.S. DDGS Physical and chemical characteristics of distiller’s dried grains with solubles (DDGS) vary among sources and can influence its feeding value and handling characteristics. These...

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