1、奈米科技,課程時程,第一週 奈米概論與量子物理 第二週 積體電路元件與製程 第三週 先進CMOS製程與元件 第四週 先進製程設備 第五週 積體光學概論 第六週 光波導學理論 第七週 積體光學元件 第八週 積體光學製程 第九週 期中考試,積體電路元件與製程,半導體物理半導體元件 PN junctionCMOS 製程,Concepts of Semiconductors,Elemental Semiconductors Si, Ge Binary Compounds GaAs, InP, GaSb, GaN, InAs, AlAs, AlP Ternary Compounds AlGaAs, In
2、GaAs, InGaP, AlGaP, InAlAs, GaAsSb Quarternary Compounds InGaAsP, AlGaAsP, InAlGaAs, AlInGaP,What are the semiconductors,Crystal Structure and Lattice,Diamond structure Si, Ge, C,Zinc-blende structure GaAs, InAs, InP,Basic lattice structure,100,110,111,Crystal planes of a semiconductor crystal,E,k,F
3、ree electron,Atomic orbital,crystal,Electrons Energy Spectrum,k,E,Semiconductors Band Structure,Ge,Si,GaAs,Reciprocal Lattice of a FCC lattice,Constant energy surface of the conduction band,Effective mass： m*Near the bottom or the top of a band, electron energy can be approximated by,Effective mass
4、is related to the curvature of the energy band,k,Heavy hole band,Light hole band,Conduction band,Effective Mass,Electrons velocity is also related to the band structure,For Si and Ge： the constant energy surface is ellipsoidal.For GaAs me* = 0.067 meSi mcl* = 0.98 me mct* = 0.19 meGe mcl* = 1.64 me
5、mct* = 0.082 me,GaAs： mhh* = 0.51 me mlh* = 0.082 me Si ： mhh* = 0.49 me mlh* = 0.16 me Ge ： mhh* = 0.28 me mlh* = 0.044 me,k=0,For valence band the maximum is at k = 0, but the energy is degenerate (2 bands have the same energy). One band has larger effective mass than the other.,Effective Mass (co
6、ntinued),Energy Bandgap vs. Lattice Constant for Various Semiconductors,AlGaAs x=0.25 Eg=1.72eV,GaAs,0.19eV,0.12eV,0.35eV 0.2eV,0.55eV 0.23eV,InP Eg=1.33eV,GaInAs Eg=0.75eV,GaSb Eg=0.72eV,InAs Eg=0.35eV,InAlAs Eg=1.5eV,AlSb Eg=1.62eV,GaSb Eg=0.72eV,0.5eV,0.4eV,Various Heterostructures,Vacuum level,B
7、and Alignment at a Heterjunction,Heterostructures and Heterostructure Devices,hn,DEc,DEv,HEMT,HBT,DH laser,Confine carriers,Blocking barriers,Separate carriers from donors,Number of States in K Space,3 D,2 D,1 D,1-D,2-D,3-D,0 E,0 E,0 E,Density of States,E,Density of States of Various Quantum Structu
8、res,D(E),E,D(E),D(E),D(E),D(E),E,E,E,Bulk,Superlattice,Quantum Well,Quantum Wire,Quantum Dot,E,k,E,k,d = l/2,DBR bandgaps in photonic crystal Control of photon modes and optical path,Mini bands in superlattice Bandgap engeering Effective mass engineering Control of electron transport,Wave nature of
9、electrons and photons Energy bands in periodic structures,P- and N- Type Semiconductors,Doping of Semiconductors,Energy Bands and Carrier Concentration,Energy Bands for Solid,Energy Bands Comments,Fermi level,Characterization by Fermi level,Fermi-Dirac Distribution,Distribution functions and compari
10、son,Maxwell-Boltzmann distribution function,Bose-Einstein distribution function,Fermi function,F. D. Distribution vs. Temperature,Fermi Function,Conduction Electron Population for Semiconductor,Electron Density of States,Concepts of Electron Density,The Fermi function gives the probability of occupy
11、ing an available energy state, but this must be factored by the number of available energy states to determine how many electrons would reach the conduction band.This density of states is the electron density of states, but there are differences in its implications for conductors and semiconductors.
12、 For the conductor, the density of states can be considered to start at the bottom of the valence band and fill up to the Fermi level, but since the conduction band and valence band overlap, the Fermi level is in the conduction band so there are plenty of electrons available for conduction. In the c
13、ase of the semiconductor, the density of states is of the same form, but the density of states for conduction electrons begins at the top of the gap.,Example,Analyze of Carrier Concentration,Intrinsic carrier density versus temperature,Example,Energy Level for Impurities in Silicon,積體電路元件與製程,半導體物理半導
14、體元件 PN junctionCMOS 製程,PN Junctions and Related Devices,Diffusion Currents,Electron,Vacancy,Dopant Impurity,Silicon at T = 0K containing a trace concentration of group V impurity atoms. There are no free charges so the crystal is still an insulator.,Silicon at T 0K, with the group V impurities ionis
15、ed and free electrons available for conduction,Interstitial Diffusion,Diffusion,Law of the Junction I.,pn(xn) = pn0 exp(VA/VT) np(xp) = np0 exp(VA/VT)Diffusion currents components Jn = Dn dn/dx Jp = -Dp dp/dxDrift currents components Jn = q n mn E and Jp = q p mp EEinstein relation,Law of the Juncti
16、on II.,Shockley equation for the diode i-v characteristic,Mass Action Law,Summary,PN junction,Junction Capacitance I,Junction Capacitance II,Capacitance,Model,Junction Breakdown,Avalanche Breakdown,Avalanche breakdown occurs when a high reverse voltage is applied to a diode and large electric field
17、is created across the depletion region. The effect is dependant on the doping levels in the region of the depletion layer. Minority carriers in the depletion region associated with small leakage currents are accelerated by the field to high enough energies so that they ionise silicon atoms when they
18、 collide with them. A new hole-electron pair are created which accelerate in opposite directions causing further collisions and ionisation and avalanche breakdown,Zener Breakdown,Zener breakdown occurs with heavily doped junction regions (ie. highly doped regions are better conductors). If a reverse
19、 voltage is applied and the depletion region is too narrow for avalanche breakdown (minority carriers cannot reach high enough energies over the distance travelled) the electric field will grow. However, electrons are pulled directly from the valence band on the P side to the conduction band on the N side. This type of breakdown is not destructive if the reverse current is limited,PIN Structure,
