MICROELECTRONICS
1 SEMICONDUCTOR MATERIALS 1 2 THERMAL PROPERTIES 25 3 SEMICONDUCTORS 33 4 METAL OXIDE SEMICONDUCTOR FIELD EFFECT TRANSISTOR 37 5 INTEGRATED CIRCUITS 51 6 INTEGRATED CIRCUIT DESIGN 60 7 DIGITAL LOGIC FAMILIES 84 8 MEMORY DEVICES 102 9 MICROPROCESSORS 123 10 D A AND A D CONVERTERS 133 CONTENTS 11 APPLICATION SPECIFIC INTEGRATED CIRCUITS 141 12 DIGITAL FILTERS 159 13 MULTICHIP MODULE TECHNOLOGY 184 14 TESTING OF INTEGRATED CIRCUITS 197 15 SEMICONDUCTOR FAILURE MODES 206 16 FUNDAMENTAL COMPUTER ARCHITECTURE 225 17 SOFTWARE DESIGN AND DEVELOPMENT 239 18 NEURAL NETWORKS AND FUZZY SYSTEMS 260 19 MACHINE VISION 285 20 A BRIEF SURVEY OF SPEECH ENHANCEMENT 311 21 AD HOC NETWORKS 322 22 NETWORK COMMUNICATION 344 23 PRINTING TECHNOLOGIES AND SYSTEMS 372 24 DATA STORAGE SYSTEMS 391 25 OPTICAL STORAGE SYSTEMS 398 1 SEMICONDUCTOR MATERIALS 1 1 INTRODUCTION 1 2 CRYSTALLINE STRUCTURES BASIC SEMICONDUCTOR MATERIALS GROUPS THREE DIMENSIONAL CRYSTAL LATTICE CRYSTAL DIRECTIONS AND PLANES 1 3 ENERGY BANDS AND RELATED SEMICONDUCTOR PARAMETERS CONDUCTION AND VALENCE BAND DIRECT GAP AND INDIRECT GAP SEMICONDUCTORS EFFECTIVE MASSES OF CARRIERS INTRINSIC CARRIER DENSITIES SUBSTITUTIONAL DOPANTS 1 4 CARRIER TRANSPORT LOW FIELD MOBILITIES SATURATED CARRIER VELOCITIES 1 5 CRYSTALLINE DEFECTS POINT DEFECTS LINE DEFECTS STACKING FAULTS AND GRAIN BOUNDARIES UNINTENTIONAL IMPURITIES SURFACE DEFECTS THE RECONSTRUCTED SURFACE 1 6 SUMMARY 1 1 INTRODUCTION A SEMICONDUCTOR MATERIAL HAS A RESISTIVITY LYING BETWEEN THAT OF A CONDUCTOR AND THAT OF AN INSULATOR IN CONTRAST TO THE GRANULAR MATERIALS USED FOR RESISTORS HOWEVER A SEMICONDUCTOR ESTABLISHES ITS CONDUCTION PROPERTIES THROUGH A COMPLEX QUANTUM MECHANICAL BEHAVIOR WITHIN A PERIODIC ARRAY OF SEMICONDUCTOR ATOMS THAT IS WITHIN A CRYSTALLINE STRUCTURE FOR APPROPRIATE ATOMIC ELEMENTS THE CRYSTALLINE STRUCTURE LEADS TO A DISALLOWED ENERGY BAND BETWEEN THE ENERGY LEVEL OF ELECTRONS BOUND TO THE CRYSTAL S ATOMS AND THE ENERGY LEVEL OF ELECTRONS FREE TO MOVE WITHIN THE CRYSTALLINE STRUCTURE I E NOT BOUND TO AN ATOM THIS ENERGY GAP FUNDAMENTALLY IMPACTS THE MECHANISMS THROUGH WHICH ELECTRONS ASSOCIATED WITH THE CRYSTAL S ATOMS CAN BECOME FREE AND SERVE AS CONDUCTION ELECTRONS THE RESISTIVITY OF A SEMICONDUCTOR IS PROPORTIONAL TO THE FREE CARRIER DENSITY AND THAT DENSITY CAN BE CHANGED OVER A WIDE RANGE BY REPLACING A VERY SMALL PORTION ABOUT 1 IN 106 OF THE BASE CRYSTAL S ATOMS WITH DIFFERENT ATOMIC SPECIES DOPING ATOMS THE MAJORITY CARRIER DENSITY IS LARGELY PINNED TO THE NET DOPANT IMPURITY DENSITY BY SELECTIVELY CHANGING THE CRYSTALLINE ATOMS WITHIN SMALL REGIONS OF THE CRYSTAL A VAST NUMBER OF SMALL REGIONS OF THE CRYSTAL CAN BE GIVEN DIFFERENT CONDUCTIVITIES IN ADDITION SOME DOPANTS ESTABLISH THE ELECTRON CARRIER DENSITY FREE ELECTRON DENSITY WHEREAS OTHERS ESTABLISH THE HOLE CARRIER DENSITY HOLES ARE THE DUAL OF ELECTRONS WITHIN SEMICONDUCTORS IN THIS MANNER DIFFERENT TYPES OF SEMICONDUCTOR N TYPE WITH MUCH HIGHER ELECTRON CARRIER DENSITY THAN THE HOLE DENSITY AND P TYPE WITH MUCH HIGHER HOLE CARRIER DENSITY THAN THE ELECTRON CARRIER DENSITY CAN BE LOCATED IN SMALL BUT CONTACTING REGIONS WITHIN THE CRYSTAL BY APPLYING ELECTRIC ELDS APPROPRIATELY SMALL REGIONS OF THE SEMICONDUCTOR CAN BE PLACED IN A STATE IN WHICH ALL OF THE CARRIERS ELECTRON AND HOLE HAVE BEEN EXPELLED BY THE ELECTRIC ELD AND THAT ELECTRIC ELD 1 SUSTAINED BY THE EXPOSED DOPANT IONS THIS ALLOWS ELECTRIC SWITCHING BETWEEN A CONDUCTING STATE WITH A SETTABLE RESISTIVITY AND A NONCONDUCTING STATE WITH CONDUCTANCE VANISHING AS THE CARRIERS VANISH THIS COMBINATION OF LOCALIZED REGIONS WITH PRECISELY CONTROLLED RESISTIVITY DOMINATED BY ELECTRON CON DUCTION OR BY HOLE CONDUCTION COMBINED WITH THE ABILITY TO ELECTRONICALLY CONTROL THE OW OF THE CARRIERS ELECTRONS AND HOLES LEADS TO THE SEMICONDUCTORS BEING THE FOUNDATION FOR CONTEMPORARY ELECTRONICS THIS FOUNDATION IS PARTICULARLY STRONG BECAUSE A WIDE VARIETY OF ATOMIC ELEMENTS AND MIXTURES OF ATOMIC ELEMENTS CAN BE USED TO TAILOR THE SEMICONDUCTOR MATERIAL TO SPECI C NEEDS THE DOMINANCE OF SILICON SEMICONDUCTOR MATERIAL IN THE ELECTRONICS AREA E G THE VERY LARGE SCALE INTEGRATED VLSI DIGITAL ELECTRON ICS AREA CONTRASTS WITH THE RICH VARIETY OF SEMICONDUCTOR MATERIALS WIDELY USED IN OPTOELECTRONICS IN THE LATTER CASE THE ABILITY TO ADJUST THE BANDGAP TO DESIRED WAVELENGTHS OF LIGHT HAS STIMULATED A VAST NUMBER OF OPTOELECTRONIC COMPONENTS BASED ON A VARIETY OF TECHNOLOGIES ELECTRONIC COMPONENTS ALSO PROVIDE A ROLE FOR NONSILICON SEMICONDUCTOR TECHNOLOGIES PARTICULARLY FOR VERY HIGH BANDWIDTH CIRCUITS THAT CAN TAKE ADVANTAGE OF THE HIGHER SPEED CAPABILITIES OF SEMICONDUCTORS USING ATOMIC ELEMENTS SIMILAR TO THOSE USED IN OPTOELECTRONICS THIS RICH INTEREST IN NONSILICON TECHNOLOGIES WILL UNDOUBTEDLY CONTINUE TO GROW DUE TO THE RAPIDLY ADVANCING APPLICATIONS OF OPTOELECTRONICS FOR THE SIMPLE REASON THAT SILICON IS NOT SUITABLE FOR PRODUCING AN EF CIENT OPTICAL SOURCE 1 2 CRYSTALLINE STRUCTURES BASIC SEMICONDUCTOR MATERIALS GROUPS MOST SEMICONDUCTOR MATERIALS ARE CRYSTALS CREATED BY ATOMIC BONDS THROUGH WHICH THE VALENCE BAND OF THE ATOMS ARE LLED WITH EIGHT ELECTRONS THROUGH SHARING OF AN ELECTRON FROM EACH OF FOUR NEAREST NEIGHBOR ATOMS THESE MATERIALS INCLUDE SEMICONDUCTORS COMPOSED OF A SINGLE ATOMIC SPECIES WITH THE BASIC ATOM HAVING FOUR ELECTRONS IN ITS VALENCE BAND SUPPLEMENTED BY COVALENT BONDS TO FOUR NEIGHBORING ATOMS TO COMPLETE THE VALENCE BAND THESE ELEMENTAL SEMICONDUCTORS THEREFORE USE ATOMS FROM GROUP IV OF THE ATOMIC CHART OTHER SEMICONDUCTOR MATERIALS ARE COMPOSED OF TWO ATOMS ONE FROM GROUP N N 4 AND THE OTHER FROM GROUP M M 4 WITH N M 8 LLING THE VALENCE BANDS WITH EIGHT ELECTRONS THE MAJOR CATEGORIES OF SEMICONDUCTOR MATERIAL ARE SUMMARIZED IN THE FOLLOWING SECTIONS ELEMENTAL IV IV SEMICONDUCTORS ELEMENTAL SEMICONDUCTORS CONSIST OF CRYSTALS COMPOSED OF ONLY A SINGLE ATOMIC ELEMENT FROM GROUP IV OF THE PERIODIC CHART THAT IS GERMANIUM GE SILICON SI CARBON C AND TIN SN SILICON IS THE MOST COMMONLY USED ELECTRONIC SEMICONDUCTOR MATERIAL AND IS ALSO THE MOST COMMON ELEMENT ON EARTH TABLE 1 1 SUMMARIZES THE NATURALLY OCCURRING ABUNDANCE OF SOME ELEMENTS USED FOR SEMICONDUCTORS INCLUDING NONELEMENTAL COMPOUND SEMICONDUCTORS FIGURE 1 1 A ILLUSTRATES THE COVALENT BONDING SHARING OF OUTER SHELL VALENCE BAND ELECTRONS BY TWO ATOMS THROUGH WHICH EACH GROUP IV ATOM OF THE CRYSTAL IS BONDED TO FOUR NEIGHBORING GROUP IV ATOMS CREATING LLED OUTER ELECTRON BANDS OF EIGHT ELECTRONS TABLE 1 1 ABUNDANCE FRACTION OF ELEMENTS OCCURRING ON EARTH OF COMMON ELEMENTS USED FOR SEMICONDUCTORS ELEMENT ABUNDANCE SI 0 28 GA 1 5 10 5 AS 1 8 10 6 GE 5 10 6 CD 2 10 7 IN 1 10 7 MICROELECTRONICS 2 IV IV IV IV IV IV IV IV IV IV IV IV IV IV IV IV SI GROUP IV V III III V III IV III V III V III V III V III V GA GROUP III AS GROUP V VI II II VI II VI II VI II VI II VI II VI II VI CD GROUP II SE GROUP VI A C B FIGURE 1 1 BONDING ARRANGEMENTS OF ATOMS IN SEMICONDUCTOR CRYSTALS A ELEMENTAL SEMICONDUCTOR SUCH AS SILICON B COMPOUND III V SEMICONDUCTOR SUCH AS GAAS C COMPOUND II VI SEMICONDUCTOR SUCH AS CDS IN ADDITION TO CRYSTALS COMPOSED OF ONLY A SINGLE GROUP IV ATOMIC SPECIES ONE CAN ALSO CREATE SEMICON DUCTOR CRYSTALS CONSISTING OF TWO OR MORE ATOMS ALL FROM GROUP IV FOR EXAMPLE SILICON CARBIDE SIC HAS BEEN INVESTIGATED FOR HIGH TEMPERATURE APPLICATIONS SIXGE1 X SEMICONDUCTORS ARE PRESENTLY UNDER STUDY TO ACHIEVE BANDGAP ENGINEERING WITHIN THE SILICON SYSTEM IN THIS CASE A FRACTION X 0 X 1 OF THE ATOMS IN AN OTHERWISE SILICON CRYSTAL IS SILICON WHEREAS A FRACTION 1 X HAS BEEN REPLACED BY GERMANIUM THIS ABILITY TO REPLACE A SINGLE ATOMIC ELEMENT WITH A COMBINATION OF TWO ATOMIC ELEMENTS FROM THE SAME COLUMN OF THE PERIODIC CHART APPEARS IN THE OTHER CATEGORIES OF SEMICONDUCTOR DESCRIBED SUBSEQUENTLY AND IS PARTICULARLY IMPORTANT FOR OPTOELECTRONIC DEVICES COMPOUND III V SEMICONDUCTORS THE III V SEMICONDUCTORS ARE PROMINENT AND WILL GAIN IN IMPORTANCE FOR APPLICATIONS OF OPTOELECTRONICS IN ADDITION III V SEMICONDUCTORS HAVE A POTENTIAL FOR HIGHER SPEED OPERATION THAN SILICON SEMICONDUCTORS IN ELECTRONICS APPLICATIONS WITH PARTICULAR IMPORTANCE FOR AREAS SUCH AS WIRELESS COMMUNICATIONS THE COMPOUND SEMICONDUCTORS HAVE A CRYSTAL LATTICE CONSTRUCTED FROM ATOMIC ELEMENTS IN DIFFERENT GROUPS OF THE PERIODIC CHART THE III V SEMICONDUCTORS ARE BASED ON AN ATOMIC ELEMENT A FROM GROUP III AND AN ATOMIC ELEMENT B FROM GROUP V EACH GROUP III ATOM IS BOUND TO FOUR GROUP V ATOMS AND EACH GROUP V ATOM IS BOUND TO FOUR GROUP III ATOMS GIVING THE GENERAL ARRANGEMENT SHOWN IN FIG 1 1 B THE BONDS ARE PRODUCED BY SHARING OF ELECTRONS SUCH THAT EACH ATOM HAS A LLED EIGHT ELECTRON VALENCE BAND THE BONDING IS LARGELY COVALENT THOUGH THE SHIFT OF VALENCE CHARGE FROM THE GROUP V ATOMS TO THE GROUP III ATOMS INDUCES A COMPONENT OF IONIC BONDING TO THE CRYSTAL IN CONTRAST TO THE ELEMENTAL SEMICONDUCTORS THAT HAVE PURELY COVALENT BONDS REPRESENTATIVE III V COMPOUND SEMICONDUCTORS ARE GAP GAAS GASB INP INAS AND INSB GAAS IS PROBABLY THE MOST FAMILIAR EXAMPLE OF III V COMPOUND SEMICONDUCTORS USED FOR BOTH HIGH SPEED ELECTRONICS AND FOR OPTOELECTRONIC DEVICES OPTOELECTRONICS HAS TAKEN ADVANTAGE OF TERNARY AND QUATERNARY III V SEMICONDUCTORS TO ESTABLISH OPTICAL WAVELENGTHS AND TO ACHIEVE A VARIETY OF NOVEL DE VICE STRUCTURES THE TERNARY SEMICONDUCTORS HAVE THE GENERAL FORM AX A 1 X B WITH TWO GROUP III ATOMS USED TO LL THE GROUP III ATOM POSITIONS IN THE LATTICE OR A BX B 1 X USING TWO GROUP V ATOMS IN THE GROUP V ATOMIC POSITIONS IN THE LATTICE THE QUATERNARY SEMICONDUCTORS USE TWO GROUP III ATOMIC ELEMENTS AND TWO GROUP V ATOMIC ELEMENTS YIELDING THE GENERAL FORM AX A 1 X BY B 1 Y IN SUCH CONSTRUCTIONS 0 X 1 SUCH TERNARY AND QUATERNARY VERSIONS ARE IMPORTANT SINCE THE MIXING FACTORS X AND Y ALLOW THE BANDGAP TO BE ADJUSTED TO LIE BETWEEN THE BANDGAPS OF THE SIMPLE COM POUND CRYSTALS WITH ONLY ONE TYPE OF GROUP III AND ONE TYPE OF GROUP V ATOMIC ELEMENT THE AD JUSTMENT OF WAVELENGTH ALLOWS THE MATERIAL TO BE TAILORED FOR PARTICULAR OPTICAL WAVELENGTHS SINCE THE MICROELECTRONICS 3