Nanotechnology 101 Series Transistors 101 Mark Lundstrom Purdue University Network for Computational Nanotechnology West Lafayette, IN USA NCN www.nanohub.org 1 what to transistors do? 2 Field-Effect Transistor Lillienfield, 1925 Heil, 1935 Bardeen, Schockley, and Brattain, 1947 “The transistor was probably the most important invention of the 20th century,” Ira Flatow, Transistorized! www.pbs.org/transistor 3 transistors integrated circuit Intel 4004 Kilby and Noyce (1958, 1959) Hoff (1971) • junction transistor, 1951 • commercial IC’s, 1961 • silicon BJT, 1954 • PMOS IC’s, 1963 ~2000 transistors • MOSFET, 1960 • CMOS invented, 1963 • NMOS IC’s, 1970 4 silicon microelectronics Silicon wafer (300 mm) Silicon “chip” (~ 2 cm x 2 cm) MPU ROM DSP Control logic RAM analog Intel TI cell phone chip 5 Transistor scaling ~ L Each technology generation: (scaling) L " L 2 A " A 2 Number of transistors per chip doubles (Moore’s Law) ! ! 6 Moore’s Law http://public.itrs.net/ > - - ) > - 10 10000 s - r ) e s t n e o r m c o i 1 1000 n m a ( n ( e z e i z s i s e 0.1 100 r e u r t u a t e nanoelectronics a F 0.01 10 e F 70 80 90 00 10 20 Year--> L = 6 nm (IBM, 2002) L = 5 nm (NEC, 20703) applications symbol switch amplifier D D D G G G S S S 8 EE fundamentals 1) Voltage 2) Current 3) Resistance 4) I-V characteristics resistor voltage source current source 5) Metals, insulators, and semiconductors 9 voltage potential energy = mgh h FG ground 10 voltage + + + + + + + + + + + + + + ++ V = E d Volts d electric field, E force F = qE - - - - - - - - - - - - - - - - - - - - - ground: V = 0 potential energy: E = qE d Joules 11 voltage + V = 1.5 V I - 12 current I + + + + + + + + + ++ I - - - - - - - - - Q I = C/sec = amperes " 13 ! resistance R I resistance (ohms W) 14 current-voltage characteristic decreasing R I increasing R V V Ohm’s Law: I = R 15 ! ideal voltage source I I + V LOAD V 0- 0 V 16 ideal current source + I I 0 + LOAD V I0 - V - 17 transistor I D + ? VDS G V VGS S - 18 metal I • good conductors Au Ag • resistance low Cu • conduction by electrons 19 insulator I glass • very poor conductors quartz • resistance very high SiO2 20 semiconductor I Si resistance greater than a Ge metal (~ 1 W) but less than an insulator (~ 106 W) GaAs 21 semiconductor doping I intrinsic semiconductor: e.g. pure Si doped semiconductor: < 1% ‘impurities’ Si p-type: boron impurities conduction by + charges n-type: phosphorus impurities conduction by - charges22 EE fundamentals √ 1) Voltage √ 2) Current √ 3) Resistance √ 4) I-V characteristics resistor voltage source current source √ 5) Metals, insulators, and semiconductors 23 building a transistor n+ poly Si SiO2 p-type silicon 24 building a transistor source gate drain n+ poly Si n+ Si p-type silicon 25 S G D 26 transistor - + VDS I D VG < VT source gate drain n+ Si p-type silicon 27 transistor I D VDS 28 transistor - + VDS I D VG > VT source gate drain n+ Si - - p-type silicon 29 transistor I D VDS 30 transistor - + VDS I D VG > VT source gate drain + - - n Si -- - p-type silicon 31 transistor: a voltage controlled resistor? I D increasing VG VDS 32 real transistors VGS G + + + + - - - - ID S D VDS VDS 33 real transistors VGS ID ID VGS VDS VDS 34 real transistors V ID GS G S D VDS VDS why does the current saturate? 35 MOSFET energy band diagrams electron energy vs. position S G D VD≈ 0V VD= VDD E = -q V 36 low VDS I1 I2 I1, I2 ~ VG ID = I1 - I2 VD = 0: I1 = 12 ID = 0 ID VD > 0: VG2 I1 > 12 V G1 ID > 0 37 VDS high VDS I1 I2 I1, ~ VG I2 ~ 0 I D I = I ~ V VG2 D 1 G VG1 38 VDS complementary CMOS VDD P-channel MOSFET VOUT VIN N-channel MOSFET 39 CMOS G G S D S D n+ Si p+ Si p-type silicon n-type silicon n-MOS: VGS > 0 p-MOS: VGS < 0 40 CMOS inverter VDD VDD P > - - T V U OUT O VIN V V N DD VIN--> “transfer characteristic” 41 CMOS inverter ID VDD > - - T U O V VDD V --> IN VDS flatter characteristic sharp transition (small dependence of I on V ) separates zero and one D DS gives sharp transition 42 Two input CMOS NAND gate V AND dd A B C 0 0 0 0 1 0 P1 P2 1 0 0 V 1 1 1 Cout V A N1 in1 NAND A B C V 0 0 1 Bin2 N2 0 1 1 1 0 1 1 1 0 43 CMOS Amplifier VDD gain VDD > - v - out VOUT T U VIN O V VDD VIN--> vin 44 transistors terminal 1 point contact transistor bipolar transistor I1 MOSFET JFET SOI MOSFET FinFET control MODFET (HEMT) heterojunction bipolar transistor velocity modulation transistor terminal 2 45.