《半导体器件物理》1.ppt

1、2020/8/17,Physics of Semiconductor Devices,1,1-1 Introduction,2020/8/17,Physics of Semiconductor Devices,2,2020/8/17,Physics of Semiconductor Devices,3,2020/8/17,Physics of Semiconductor Devices,4,2020/8/17,Physics of Semiconductor Devices,5,2020/8/17,Physics of Semiconductor Devices,6,2020/8/17,Phy

2、sics of Semiconductor Devices,7,2020/8/17,Physics of Semiconductor Devices,8,2020/8/17,Physics of Semiconductor Devices,9,2020/8/17,Physics of Semiconductor Devices,10,2020/8/17,Physics of Semiconductor Devices,11,2020/8/17,Physics of Semiconductor Devices,12,2020/8/17,Physics of Semiconductor Devic

3、es,13,2020/8/17,Physics of Semiconductor Devices,14,2020/8/17,Physics of Semiconductor Devices,15,2020/8/17,Physics of Semiconductor Devices,16,2020/8/17,Physics of Semiconductor Devices,17,2020/8/17,Physics of Semiconductor Devices,18,2020/8/17,Physics of Semiconductor Devices,19,2020/8/17,Physics

4、of Semiconductor Devices,20,2020/8/17,Physics of Semiconductor Devices,21,2020/8/17,Physics of Semiconductor Devices,22,2020/8/17,Physics of Semiconductor Devices,23,2020/8/17,Physics of Semiconductor Devices,24,1-2 Crystal Structure,2020/8/17,Physics of Semiconductor Devices,25,Solid state material

5、s includes: insulator, semiconductors and conductors.,Semiconductor materials,2020/8/17,Physics of Semiconductor Devices,26,Compounds Semiconductors A binary compound semiconductors is a combination of two elements from the periodic table. Ex: GaAs , GaPetc.Ternary and quaternary compounds. Ex:GaxIn

6、1-xAsyP1-y,Element the free electrons can participate in current conduction. When electrons leave the covalent bond, the vacancies were considered as a particle similar to an electron. This fictitious particle is called a hole.,2020/8/17,Physics of Semiconductor Devices,51,1-3 Energy Bands,2020/8/17

7、,Physics of Semiconductor Devices,52,Wave-Particle Duality,Wave-particle duality applies primary to small particles, such as electron, neutron, photon Waves behaves as if they are particles and sometimes particles behaves as if they are waves,De Broglie relationship,2020/8/17,Physics of Semiconducto

8、r Devices,53,One-electron Approximation,2020/8/17,Physics of Semiconductor Devices,54,Hydrogen Atomic Model,Bohrs Model,2020/8/17,Physics of Semiconductor Devices,55,Hydrogen Atomic Model,For an atom, each electron must have a separate distinct energy state defined by 4 quantum numbers:,Principe qua

9、ntum number, n=1,2,3,Angular momentum quantum number, I=0,1,2,n-1,Magnetic quantum number, m=0,1, ,I,Electron spin, s=1/2,Only hydrogen atom can be solved due to electron-electron interaction,2020/8/17,Physics of Semiconductor Devices,56,2020/8/17,Physics of Semiconductor Devices,57,Energy Band,2020

10、/8/17,Physics of Semiconductor Devices,58,Energy Band,Schematic showing the splitting of three energy states into allowed bands of energies,2020/8/17,Physics of Semiconductor Devices,59,Band Formation,Si Atom Interaction,p orbital: six allowed states s orbital: two allowed states,2020/8/17,Physics o

11、f Semiconductor Devices,60,Energy Band,Schematic diagram of the formation of a silicon crystal from N isolated silicon atoms,2020/8/17,Physics of Semiconductor Devices,61,Energy Band,2020/8/17,Physics of Semiconductor Devices,62,Energy Momentum Diagram,For a free electron,energy E can be given by,m0

12、: effective massP: momentum,2020/8/17,Physics of Semiconductor Devices,63,Bolch Electron Wavefunction,In periodic potential, an electron will behave in this manner, i.e., Bloch electron,is also periodic,2020/8/17,Physics of Semiconductor Devices,64,Energy (E) vs. Wavevector(k),Free Electron:,In crys

13、tal, free-electron E-k is no longer valid, discontinuity at k=n/a emerges. Creating energy gap,2020/8/17,Physics of Semiconductor Devices,65,Brillouin ZoneReduced Brillouin Zone,2020/8/17,Physics of Semiconductor Devices,66,Energy (E) vs. Wavevector(k),2020/8/17,Physics of Semiconductor Devices,67,E

14、ffective Mass Concept,Electrons in conduction band and holes in valence band are similar to free electrons since they can move relatively freely,We can treat electrons and holes as classical particles,2020/8/17,Physics of Semiconductor Devices,68,Effective Mass Concept,2020/8/17,Physics of Semicondu

15、ctor Devices,69,Energy Band Diagram of Silicon,Eg=1.12eV,kT/q=0.0259eV300k,2020/8/17,Physics of Semiconductor Devices,70,Energy Band: Temperature Effect,Band Gap vs. Temperature,Si,GaAs,2020/8/17,Physics of Semiconductor Devices,71,Energy Band,Conductor , Semiconductor & insulator,2020/8/17,Physics

16、of Semiconductor Devices,72,Band Structure,Direct Semiconductor,The top of the highest (occupied) valence band and the bottom of the lowest (unoccupied) conduction band are at the same value in k-space. Examples: GaAs, InP, GaN, ZnO.,2020/8/17,Physics of Semiconductor Devices,73,Band Structure,Indir

17、ect Semiconductor:,The extreme at the top of the valence bandand at the bottom of the conduction bandare at different k-values.Examples: Ge, Si.,2020/8/17,Physics of Semiconductor Devices,74,Donor & Acceptor,Deep impurity Level & Shallow Impurity Level,2020/8/17,Physics of Semiconductor Devices,75,1

18、-4 Carrier Concentration at Thermal Equilibrium,2020/8/17,Physics of Semiconductor Devices,76,Distribution Functions and Densities of States,Let us consider the situation when the number of states is much greater than the number of particles and the probability of finding a particle in a given states is much smaller