染料敏化太阳能课件

1、課程講義 半導體概論南台科技大學光電系 吳坤憲 1I. 半導體材料 (Materials)II. 半導體基本物理 (Physics)III. 半導體元件 (Devices)IV. 半導體製程 (Fabrication)V. 半導體 量測 (Characterization)Introduction to Semiconductor Technologies2Chapter ISemiconductor Materials半導體材料35W for SemiconductorsWhat?導電性界於導体與絕緣體之間的材料Why? 半導體為現代電子工業的核心Where? 應用於幾乎所有的電子產品(元件

2、)When? 1988年起電子工業成為世界上最大規模的工業How? 導電性可控制5What are Semiconductors?入門導電性界於導体與絕緣體之間的材料中階電阻係數約為10-4 108 -cm的材料進階能隙約在 4eV以下之的材料6Solid-State MaterialsConductorMn: 105Cu: 8 106Fe: 107SemiconductorSi: 105 doped-Si: 105 10-5 InsulatorQuartz: 10-18Plastics: 10-13GaAs: 10-6Resitivity (-cm)Conductivity (-cm)-17

3、Portion of the Periodic Table related to semiconductors8Applications of Semiconductors Device10其他常用的半導體材料之相關名詞Bulk (本體)Substrate (基板)Film (薄膜)Epitaxial layer (磊晶層)12重要的半導體分類Element semiconductorCompound semiconductorIntrinsic semiconductorExtrinsic semiconductorDirect semiconductorIndirect semicondu

4、ctorDegenerate semiconductorNon-degenerate semiconductorCompensated semiconductorNon-compensated semiconductor14Crystallization of materials15Crystal and LatticeCrystal (結晶體)The semiconductor materials are basically assumed as single crystals to simplify the analysis.Lattice (晶格)The periodic arrengm

5、ent of atoms in a crystalLattice Constant (晶格常數)The dimension a is called the lattice constantThree cubic-crystal unit cells. (a) Simple cubic. (b) Body-centered cubic (c) Face-centered cubic.16The Diamond Structure(a) Diamond lattice. (b) Zincblende lattice.17Crystal Plane and DirectionMiller indic

6、es of some important planes in a cubic crystalA (623)-crystal plane18Conduction Electron and HoleFormation of intrinsic carriers20Donor and AcceptorFormation of extrinsic carriers21Simplified Energy-Band Diagram23Energy-Momentum Band Diagram24Direct and Indirect Bandgap SemiconductorsDirect transiti

7、on: band to band photon emissionIndirect transition: via defect or impurity-related states phonon emissionDirect BandgapIndirect Bandgap26Effective Mass等效質量是量子力學與古典力學之重要橋樑電子與電洞可以被視為古典物理中之帶電粒子。mn* (d2E/dp2)-1等效質量等於能量-動量曲線中曲率的倒數。曲率越小，等效質量越大。拋物線的開口越大，等效質量越大。電洞的等效質量大於電子等效質量mp* mn* For Si: mn* = 0.26 m0,

8、 mp* = 0.69 m0For GaAs: mn* = 0.063 m0, mp* = 0.57 m027Fermi Level費米能階(EF)為被電子佔有機率為1/2的能量。費米分布函數對稱於費米能階。F(E) exp-(E-EF)/kT for (E-EF) 3kTF(E) 1- exp-(E-EF)/kT for (E-EF) 3kT在室溫下，能量高於(低於) 3KT之能階可視為空態(滿態)28Carrier Concentration電子濃度為態位密度(density of state) N(E)與費米分布函數(Fermi distribution) F(E)之摺積(convolu

9、tion)。n = Nc exp exp-(Ec-EF)/kT 電洞濃度為態位密度(density of state) N(E)與1-F(E)之摺積(convolution)。p = Nv exp exp-(EF-Ev)/kT費米能階的位置決定了載子濃度。若 n = p = ni 時，EFi = (Ec + Ev)/2 + kT/2 ln(Nv / Nc) (Ec + Ev)/2 at 300 K 。稱為本質濃度 (intrinsic concentration) ni2 = Nc Nv exp (-Eg/KT)ni 1010 cm-3 for Si and 106 cm-3 for GaAs

10、本質濃度為半導體材料之重要參數。30Intrinsic, N-type and P-type semiconductors(1) Intrinsic(2) N-type(3) P-type31Fermi Level in Energy-band diagram32Various Impurities33Intrinsic and Extrinsic SiliconIntrinsic Semiconductor (本質半導體)導電電子數量與電洞數量大約相同的半導體通常指未經摻雜的半導體(Undoped Semiconductor)N-type Semiconductor (N型半導體)多數載子(

11、majority carrier)為電子的半導體矽晶體中摻雜V 族原子則形成N型半導體P-type Semiconductor (P型半導體)多數載子(majority carrier)為電洞的半導體矽晶體中摻雜III族原子則形成P型半導體34Impurities for III-V Compound SemiconductorsDonor (施體)Column VI (S, Se,Te, etc.) impurity substitute for column V (As)Acceptor(受體)Column II (Be, Zn, Cd, etc.) impurity substitute for column III (Ga)Amphoteric impurity (雙性雜質)Column IV (Si)substituting Ga for donor (low T)substituting As for acceptor (high T)35Carrier Concentration vs. Temperat