Ud W. hl
Epitaxy of Semiconductors
Intr d t n t h l r n pl
4) Springer Contents
1 Introduction 1 1.1 Epitaxy 1 1.1.1 Roots of Epitaxy 1 1.1.2 Epitaxy and Bulk-Crystal Growth 4 1.2 Issues of Epitaxy 4 1.2.1 Convention an Use of the Term "Atom" 4 1.2.2 Assembly of Atoms 5 1.2.3 Tasks for Epitaxial Growth 6 References 9 2 Structural Properties of Heterostructures 11 2.1 Basic Crystal Structures 11 2.1.1 Notation of Planes and Directions 11 2.1.2 Wafer Orientation 13 2.1.3 Face-Centered Cubic and Hexagonal Close-Packed Structures 13 2.1.4 Zincblende and Diamond Structures 14 2.1.5 Rocksalt and Cesium-Chloride Structures 16 2.1.6 Wurtzite Structure 16 2.1.7 Thermal Expansion 17 2.1.8 Structural Stability Map 19 2.1.9 Polytypism 20 2.1.10 Random Alloys and Vegard's Rule 21 2.1.11 Virtual-Crystal Approximation 26 2.2 Elastic Properties of Heterostructures 26 2.2.1 Strain in One and Two Dimensions 26 2.2.2 Three-Dimensional Strain 27 2.2.3 Hooke's Law 29 2.2.4 Poisson's Ratio 2.2.5 Pseudomorphic Heterostructures 2 2.2.6 Critical Layer Thickness 35
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2.2. Appr h t Ext nd th Cr t l h n 2.2.8 rt ll l x d r nd h r l M t h 42 2. l t n 44 2. . Ed nd S r l t n 4 2. .2 l t n t r 46 2. . l t n n th f Str t r 4 2. .4 l t n n th nd nd n bl nd Str t r 4 2. . l t n En r 2. .6 l t n n th h p nd W rtz t Str t r 4 2. . M Cr t l 2.4 Str t r l Ch r t r z t n U n ffr t n 8 2.4. r 8 2.4.2 h Str t r t r 2.4. h pr l tt 6 2.4.4 h E ld C n tr t n 6 2.4. h l t n S n n th pr l Sp 64 2.4.6 pr l Sp M p 6 2. r bl Ch p. 2 0 2.6 G n r l d n Ch p. 2 f r n 4 El tr n r p rt f t r tr t r . l r p rt . . El tr n nd f n bl nd nd W rtz t Cr t l . . .2 Str n Eff t 8 . . p r t r p nd n f th nd p 8 . .4 nd p f All 88 .2 nd Off t 0 .2. El tr n Aff n t l .2.2 C n An n l 2 .2. M d l f p I p r t v l .2.4 Int rf p l h r .2. M d l S l d h r 6 .2.6 Off t f S I v l nt t r tr t r .2. nd Off t f t r v l nt Int rf .2.8 nd Off t f All 0 . El tr n St t n n n l Str t r 0 . . n n l t f th El tr n n t f St t 02 . .2 Ch r t r t S l f r S z Q nt z t n 06 . . Q nt W ll 0 . .4 Q nt W r 2 . . Q nt t 6 .4 r bl Ch p. 2 . G n r l d n Ch p. 2 f r n 2 Contents ix
4 h r d n f Ep t x l r Gr th 4. h E l br 4. . h r d n E l br 2 4. .2 G bb h l 4 4. . G bb En r f S n l C p n nt S t 4. .4 h nd r n S n l C p n nt S t 4. . r v n r f r Cr t ll z t n 40 4. .6 C p n nt S t 4 4.2 Cr t ll n Gr th 48 4.2. n hr n n l l t n 48 4.2.2 t r n hr n n l l t n 2 4.2. Gr th M d 4 4.2.4 E l br S rf 4.2. n n l l t n 6 4.2.6 I l nd Gr th nd C l n 64 4.2. Gr th th t l t n 66 4.2.8 p n n r Aft r Gr th Int rr pt n 68 4. r bl Ch p. 4 68 4.4 G n r l d n Ch p. 4 6 f r n 6 At t A p t f Ep t x l r Gr th . S rf Str t r . . h K n S t f K l Cr t l 2 . .2 S rf f K l Cr t l . . l x t n nd n tr t n . .4 El tr n C nt n M d l 6 . . n t t n f S rf n tr t n . .6 n tr t n f th G A (00 S rf 8 . . h S l n ( ( x n tr t n 84 .2 K n t r St p n r Gr th 86 .2. K n t n th rr St p K n M d l 86 .2.2 At t r n l t n nd Gr th 88 .2. Ad t n rr d S rf 2 .2.4 Gr th b St p Adv n 4 .2. h Ehrl h S h b l rr r .2.6 Eff t f th Ehrl h S h b l rr r n S rf St p .2. h n n f S rf St p 20 .2.8 Gr th f S (I ( x S rf 204 .2. Gr th f G A (00 ß2(2 x 4 S rf 20 . S lf r n z d n tr t r 20 . . Str n Kr t n I l nd Gr th 20 . .2 h r d n r K n t n I l nd r t n 2 . . W r Gr th n n pl n r S rf 2 x Contents
5.4 Problems Chap. 5 220 5.5 General Reading Chap. 5 221 References 221 6 p n , ff n, nd C nt t 225 6.1 Doping of Semiconductors 225 6.1.1 Thermal Equilibrium Carrier-Densities 226 6.1.2 Solubility of Dopants 231 6.1.3 Amphoteric Dopants 235 6.1.4 Compensation by Native Defects 236 6.1.5 DX Centers 239 6.1.6 Fermi-Level Stabilization Model 241 6.1.7 Delta Doping 243 6.2 Diffusion 247 6.2.1 Diffusion Equations 247 6.2.2 Diffusion Mechanisms 250 6.2.3 Effective Diffusion Coefficients 252 6.2.4 Disordering of Heterointerfaces 255 6.3 Metal-Semiconductor Contact 259 6.3.1 Ideal Schottky Contact 259 6.3.2 Real Metal-Semiconductor Contact 263 6.3.3 Practical Ohmic Metal-Semiconductor Contact 265 6.3.4 Epitaxial Contact Structures 267 6.4 Problems Chap. 6 270 6.5 General Reading Chap. 6 271 References 271 M th d f Ep t x 275 7.1 Liquid-Phase Epitaxy 276 7.1.1 Growth Systems 277 7.1.2 Congruent Melting 279 7.1.3 LPE Principle 281 7.1.4 LPE Processes 283 7.2 Metalorganic Vapor-Phase Epitaxy 286 7.2.1 Metalorganic Precursors 287 7.2.2 The Growth Process 290 7.2.3 Mass Transport 293 7.3 Molecular Beam Epitaxy 299 7.3.1 MBE System and Vacuum Requirements 300 7.3.2 Beam Sources 302 7.3.3 Uniformity of Deposition 307 7.3.4 Adsorption of lmpinging Particles 309 7.4 Problems Chap. 7 310 7.5 General Reading Chap. 7 311 References 311 C nt nt x
App nd x An r t r bl 315 Ind x 3 19 nd nt l h l C n t nt 325