SEMICONDUCTOR DEVICE PHYSICS AND DESIGN

9.5. MOSFET OPERATION 457 Ohmic region DRAIN CURRENT ID DRAIN TO SOURCE BIASVD Electron velocity ~ VS= 1.1 X 107 cm/s VD = VDsat ...

458 CHAPTER 9. FIELD EFFECT TRANSISTORS: MOSFET I-V curve in the ohmic region Intercept is turn-on voltage VT VG VT ID 0 μn Cox ...

9.5. MOSFET OPERATION 459 be exploited. In figure 9.17 we show ann-channel MOSFET showing the source-to-body bias, which is chos ...

460 CHAPTER 9. FIELD EFFECT TRANSISTORS: MOSFET Ιnversion Condition When Ec VSB = 0 EFi EF Ev eVs = –2eφF (b) Ιnversion Conditio ...

9.5. MOSFET OPERATION 461 The saturation current is now, from equation 9.5.11, ID(sat)= (25× 10 −^4 )(600) 2(1. 5 × 10 −^4 ) (3. ...

462 CHAPTER 9. FIELD EFFECT TRANSISTORS: MOSFET The oxide areal capacitance is Cox= ox dox = 3 .9(8. 84 × 10 −^14 ) 500 × 10 −^ ...

9.5. MOSFET OPERATION 463 A typical n-channel depletion mode device Ohmic Region Drain Current ID Drain Bias VD Saturated Region ...

464 CHAPTER 9. FIELD EFFECT TRANSISTORS: MOSFET Vout t t t Vin ID Vin Vout D D S S +V p-channel n-channel +++ +++ NMOS: OFF PMOS ...

9.5. MOSFET OPERATION 465 Thus thep-channel is ON and then-channel is OFF so that the output voltage isVout=V.No current flows i ...

466 CHAPTER 9. FIELD EFFECT TRANSISTORS: MOSFET or Na^2 D = ΔVTCox e = (0.5)(3. 9 × 8. 85 × 1014 ) (1. 6 × 10 −^19 )(5× 10 −^6 ) ...

9.6. IMPORTANT ISSUES IN REAL MOSFETS 467 ln IDS 60 mV/decade of current VG-Vth 0 Figure 9.20: Observation: The device current d ...

468 CHAPTER 9. FIELD EFFECT TRANSISTORS: MOSFET S D N+ N+ A A' B B' ox φ F C V iB φ F C V iB c(x) φ B Fnc= FNsource+ c(x) FNc= F ...

9.6. IMPORTANT ISSUES IN REAL MOSFETS 469 S D N+ A A' B B ' nweak inversion EFN source EFN(x) EFN drain EC EC EFB EiB eVG Along ...

470 CHAPTER 9. FIELD EFFECT TRANSISTORS: MOSFET Vox EC EV EiB qVch(x) EFn ch(x) ~~~~ qVg EFB S D N+ N+ S D N+ N+ EFN source EFN ...

9.6. IMPORTANT ISSUES IN REAL MOSFETS 471 S D N+ A A' B B’ nweak inversion EFN source EFN(x) EFN drain φBS nsource = NCexp –(φBS ...

472 CHAPTER 9. FIELD EFFECT TRANSISTORS: MOSFET ⎟ ⎟ ⎠ ⎞ ⎜ ⎜ ⎝ ⎛ ∝ G bias E V Band to Band tunneling exp Figure 9.25: As gate len ...

9.6. IMPORTANT ISSUES IN REAL MOSFETS 473 by equation 9.3.5. Thus, if the sheet chargensincreases the surface field also increas ...

474 CHAPTER 9. FIELD EFFECT TRANSISTORS: MOSFET 108 107 106 (^105102 103 104 105 106) ...

9.6. IMPORTANT ISSUES IN REAL MOSFETS 475 n+ n+ n+ n+ Inversion charge S (a) p-type VGS L VDS VDS = VDS(sat) Inversion charge S ...

476 CHAPTER 9. FIELD EFFECT TRANSISTORS: MOSFET IDS Vth (short channel) Vth (long channel) VGS S D N+ N+ - - - - - - --- - - - - ...