lec0-intro.ppt - 2020 ECE260A Introduction continued 1 Introduction Integrated circuits many transistors on one chip Very Large Scale Integration(VLSI

lec0-intro.ppt - 2020 ECE260A Introduction continued 1...

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2020 ECE260A Introduction, continued. 1
2 Introduction Integrated circuits: many transistors on one chip. Very Large Scale Integration (VLSI): billions! Complementary Metal Oxide Semiconductor Fast, cheap, low power transistors Today: How to build simple CMOS chips CMOS transistors Building logic gates from transistors Transistor layout and fabrication Rest of the course: How to build a good CMOS chip
3 Silicon Lattice Transistors are built on a silicon substrate Silicon is a Group IV (tetravalent) material Forms crystal lattice with bonds to four neighbors Si Si Si Si Si Si Si Si Si Fig1.7A in textbook.
GaN It’s not all silicon, although that still dominates baseband apps. More than two decades after the first demonstration, gallium nitride (GaN) wide bandgap (WBG) semiconductors are revolutionizing an increasing number of applications from power electronics, RF communications, to light-emitting diode (LED) lighting, photovoltaic solar cells, integrated nanophotonics, and more. 4
GaN 5 What is wrong w/ the picture on the left? This is from Panasonic marketing material
GaN GaN WBG power device technology is increasing energy efficiency and transforming the electric grid from a passive one to an actively controlled physical- cyber system. Economic (>$40G/yr. electricity savings) and environmental (equivalent of 300 coal fired power plants) benefits Critical for new device concepts and system architectures which will radically change the way we generate, distribute, and consume electricity every day. 6
7 Dopants Silicon is a semiconductor Pure silicon has no free carriers and conducts poorly Adding dopants increases the conductivity Group V: extra electron (n-type) As Group III: missing electron, called hole (p-type) B As Si Si Si Si Si Si Si Si B Si Si Si Si Si Si Si Si - + + - P-type
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9 p-n Junctions p-type and n-type semiconductor junction = diode. Current flows only in one direction hole flow: left to right in this picture p-type n-type anode cathode Electron mobility =2-3X of holes + side of battery goes here for forward bias Fig 1.8
10 nMOS Transistor Four terminals: gate, source, drain, body Gate – oxide – body stack looks like a capacitor Gate and body = conductors – SiO 2 (oxide) = good insulator Called metal – oxide – semiconductor (MOS) capacitor (gate is often no longer metal*) * Metal gates are returning today!
11 nMOS Operation Body is often tied to ground (0 V), particularly in an integrated circuit. (Exceptions include top NMOS in 2-input NAND.) Gate voltage < threshold: P-type body is at low voltage Source-body and drain-body diod es are OFF No current flows, transistor is OFF no free electrons no channel
12 nMOS Operation Cont.

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