1. ELECTRONICS I Instructor: Eng.Moayed N. EL Mobaied The Islamic University of Gaza Faculty of Engineering Electrical Engineering Department بسم الله الرحمن الرحيم EELE 2321 — Spring 2010 Lecture 2

2. Semiconductor materials Materials ConductorInsulatorSemiconductor Cupper, Gold, Aluminum …etc Wood, Mica, Plastic…etc Silicon, Germanium …etc

3. Semiconductor materials Atoms Electron(-)Proton(+)Neutron (No) Proton +Neutron = Nucleus

4. Semiconductor materials Conductor Cupper

5. Semiconductor materials Semiconductor Silicon

6. Semiconductor materials Idea : Electronics are how to control of 1- Current pass 2- Current flow (Semiconductors)

7. Semiconductor materials (Semiconductors) Compound –crystal Silicon Single –crystal Germanium Gallium arsenide Gallium Nitride SiGeGaAsGaN

8. Germanium: (1947) Easy to find. Sensitive to changes in temperature. Silicon: (1954) Less sensitive to changes in temperature. Widely used. Gallium arsenide: ( 1970) Speed of operation up to 5 times Si. More expensive. Semiconductor materials

9. Silicon = 14 Germanium = 32 Gallium = 31 Arsenic = 33 4 valence= tetravalent 5 valence= pentavalent Valence : Potential (ionization potential) less than other electrons in other shell.

10. Semiconductor materials Covalent bonding Pure silicon Single-crystal 8 Electrons in outside doping Intrinsic Extrinsic

11. Semiconductor materials Covalent bonding GaAs Compound- crystal

12. Semiconductor materials Covalent bonding Valence electrons Absorb kinetic energy Break Covalent bond Free state Very sensitive to any applied electric fields Thermal energyLight energy Intrinsic carriers = Free electron due to external causes

13. Semiconductor materials Intrinsic Carriers (per cubic centimeter) semiconductor 1.7*10 6 GaAs 1.5*10 10 Si 2.5*10 13 Ge

14. Semiconductor materials Relative mobility factor (µ n ) semiconductor 1500Si 3900Ge 8500GaAs Ability of the free carriers to move throughout the material

15. Semiconductor materials Conductors: Positive temperature coefficient ( # carriers slightly increase in heat, But their vibration pattern about a relatively fixed location make it difficult to flow through the material) Semiconductors : Negative temperature coefficient (kinetic energy)

16. Semiconductor materials Energy level

17. Semiconductor materials Energy level End of Lecture **** Eng.moayed