电子器件场效应晶体管.ppt
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1、6.4.3 Effects of real surfaces alkali metal ions 碱金属离子碱金属离子sodium(Na+)ion 钠离子钠离子mobile charge可动电荷可动电荷trapped charge陷阱电荷陷阱电荷interface charge界面电荷界面电荷fixed charge固定电荷固定电荷effective positive charge有效正电荷有效正电荷heavily doped poly-silicon重掺杂多晶硅重掺杂多晶硅MOS Structure Poly-silicon-OS StructureIdeal MOS capacitance
2、Real Surface Effects:Work function difference&interface chargeNon-ideal capacitance(1)work function difference semiconductoroxiden+polysilicon(多晶硅)ms=m-sn+poly-n Sin+poly-p SiIdealNon-ideal(EFm-EFs)=(qs-qm)V=s-mVG=VFB(平带电压平带电压)=-V=m-s=ms(2)Interface chargeGenerally,there are four types of charges in
3、 a practical MOS structure.Mobile ionic charge Qm可动离子电荷Oxide trapped charge Qot氧化物陷阱电荷Oxide fixed charge Qf氧化物固定电荷Interface trap charge Qit界面陷阱电荷IdealInterface chargeQiEffects of real surface 6.4.4 Threshold voltageTo achieve the flat bandTo accommodate the depletion chargeTo induce the inverted reg
4、ionQd=-qNaWm(n channel/P-sub)Qd=qNdWm(p channel/N-sub)When is the threshold voltage of p-channel MOSFET greater than 0?How to do?1)flat band voltage2)threshold voltage3)depletion mode because VT0(4)MOS Capacitor (ideal)Capacitance-voltage characteristics(电容电压特性)CiCsBecause Cs is depending on VG,the
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- 电子器件 场效应 晶体管
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