固体物理导论 1.ppt

1、Introduction to Solid-state Physics固体物理导论,Yu Bai 白煜 Suzhou School for Nano-Science and Nano-Engineering, Xian Jiaotong University 西安交通大学苏州纳米科学与工程技术学院,References,固体物理 Charles Kittel 半导体器件物理 S.M. Sze/ 施敏,Introduction to Solid-state PhysicsLecture 1,10/10/2012,Innovation is not just brilliance from one

2、 man,Inside a Chip,500nm,n: neutron， p: proton,Covalent bonding for Si atoms Z = 14: 1s22s22p63s23p2,Basic semiconductor theory,Valence band model Energy band model Density of states functions Fermi-Dirac distribution function Intrinsic and extrinsic carrier concentration,The following slides are fr

3、om Professor CHOI WEE KIONGDepartment of Electrical & Computer EngineeringNational University of Singapore,Valence band model of solids,The outmost shell electrons of an atom are valence electrons. Bonding of electrons is based on valence electrons. Frequently, the driving force for bonding is to ha

4、ve 8 (or sometimes 18) electrons for the outmost shell to achieve a complete shell.,Covalent bonding for Si atoms Z = 14: 1s22s22p63s23p2,4 valence electrons,Sharing of 1 pair of valence electrons between adjacent atoms,Valence band model of solids (cont.),Silicon at T = 0 K,Silicon at T 0 K,Valence

5、 band model of solids (cont.),Energy band model of solids,Typical energy band versus distance plot at T = 0,Valence band model of Si,T = 0K,T 0K,Band gap of semiconductors,Band gap for Si,e.g. Eg = 1.115eV at 300K,Density of states function,Near the bottom of the conduction band (i.e. for electrons)

6、,Near the top of the valence band (i.e. for holes),Fermi-Dirac distribution function,Probability that an empty state is occupied by an electron,Similar to Maxwell-Boltzmann density function,Electron,Hole,Equilibrium carrier concentration,where Nc and Nv are the effective density of states in the con

7、duction band and valence bands, respectively.,After integration,Equilibrium carrier concentration (cont.),Effect of low and high temperature,Low temp,High temp,恩里科费米 Enrico Fermi,多个量子力学基本概念的提出者 杨振宁，李政道的老师 曼哈顿计划的主要科学家 1938年诺贝尔物理学奖 /wiki/%E6%81%A9%E9%87%8C%E7%A7%91%C2%B7%E8%B4%B9

8、%E7%B1%B3 /wiki/Enrico_Fermi /nobel_prizes/physics/laureates/1938/fermi-bio.html,Equilibrium carrier concentration (cont.),Effect of shifting Ef closer to the Ec,Intrinsic carrier concentration and intrinsic Fermi level,ni for Si at T = 300k is 1.45x1010

9、cm-3,Summary of intrinsic semiconductor,g(E),Extrinsic or doped semiconductors,n-type semiconductor,Free electron (-),p-type semiconductor,Free hole (+),n-type with donor,p-type with acceptor,Extrinsic or doped semiconductors (cont.),Degenerate semiconductor,Non-degenerate semiconductor (i.e. Boltzm

10、ann approximations),Carrier concentration in doped semiconductors,Assuming complete ionization of dopants at elevated temperatures,Using,Charge neutrality,Fermi level in doped semiconductors,At room temperature, the carrier conc. in degenerate Si,n-type semiconductor,p-type semiconductor,Fermi level

11、 in doped semiconductors (cont.),(n-type),(p-type),RT,Distance between Ef and Ei is a log fct of dopant conc.,n-type,p-type,Non-degenerate,degenerate,degenerate,Quasi-Fermi level (non-equilibrium),Carrier concentration at high temperature,Nc & NV T3/2 ni increases rapidly with T At high T, ni dopant conc., devices no longer work as they should,Electron conc. vs. 1/T,ni Nd = 1015 cm-3 at T = 500K,Carrier mobility,I becomes important,L dominates,Velocity saturatio