Lecture 7Electronic Properties of SiliconBond Model for SiliconThermal Equilibrium (Pure Si)Doping with Group V ElementsDoping with Group III ElementsMass Action LawCompensationCompensation (cont.)R. T. HoweEECS 105 Spring 2002 Lecture 7Dept. of EECSUniversity of California at BerkeleyLecture 7• Last time:–Underdamped2ndorder transfer functions • Today :– Bode plots for general transfer functions– Start: semiconductor properties of SiR. T. HoweEECS 105 Spring 2002 Lecture 7Dept. of EECSUniversity of California at BerkeleyElectronic Properties of Silicon• Silicon is in Group IV – Electronic structure: 1s22s22p63(sp)4– Diamond lattice, with 0.235 nm bond length• Very poor conductor at room temperature: why?R. T. HoweEECS 105 Spring 2002 Lecture 7Dept. of EECSUniversity of California at BerkeleyBond Model for SiliconR. T. HoweEECS 105 Spring 2002 Lecture 7Dept. of EECSUniversity of California at BerkeleyThermal Equilibrium (Pure Si)• Balance between generation and recombination determines no= po• Strong function of temperature: T = 300 KR. T. HoweEECS 105 Spring 2002 Lecture 7Dept. of EECSUniversity of California at BerkeleyDoping with Group V Elements• P, As: extra bonding electron … lost to crystal at room temperatureR. T. HoweEECS 105 Spring 2002 Lecture 7Dept. of EECSUniversity of California at BerkeleyDoping with Group III Elements• Boron: 3 bonding electrons Æ one bond is unsaturatedR. T. HoweEECS 105 Spring 2002 Lecture 7Dept. of EECSUniversity of California at BerkeleyMass Action Law• Balance between generation and recombination: 2ioonnp =⋅• N-type case: • P-type case:R. T. HoweEECS 105 Spring 2002 Lecture 7Dept. of EECSUniversity of California at BerkeleyCompensation• Dope with both donors and acceptorsR. T. HoweEECS 105 Spring 2002 Lecture 7Dept. of EECSUniversity of California at BerkeleyCompensation (cont.)• More donors than acceptors: Nd> Na=on• Hole
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