2. 1 LINLITHGOW ACADEMY PHYSICS DEPARTMENT MOSFETs

3. 2 MOSFETS: CONTENT STATEMENTS Describe the structure of an n-channel enhancement MOSFET using the terms: gate, source, drain, substrate, channel, implant and oxide layer. Explain the electrical ON and OFF states of an n-channel enhancement MOSFET. State that an n-channel enhancement MOSFET can be used as an amplifier.

4. 3 FIELD EFFECT TRANSISTOR P-type silicon nn Substrate Metal contacts Insulating Oxide

5. 4 FIELD EFFECT TRANSISTOR P-type silicon nn Substrate Metal contacts Insulating Oxide

6. 5 FIELD EFFECT TRANSISTOR P-type substrate nn SourceGate Drain

7. 6 Circuit Symbol for MOSFET Source Gate Drain

8. 7 How MOSFETS Work Source Gate Drain Drain more positive than source

9. 8 Switching the MOSFET on P-type substrate nn Source GateDrain + _ Source Gate Drain + + + + _ No current between the source and drain due to reverse biased junctions formed by the source and substrate.

10. 9 FIELD EFFECT TRANSISTOR P-type substrate nn SourceGate Drain + + + _ _ _ _ _ + N-channel formed by electrons

11. 10 How MOSFETS Work Source Gate Drain V GS V DS Electron flow _ +

12. 11 The Transistor Switch V GS V DS Electron flow _ + Load V GS greater than the threshold voltage (about 2 V) turns on transistor

13. 12 The Transistor Amplifier V in V DS _ + Load Voltage Amplification = V out / V in R2R2 R1R1 V out 0 V