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nanocrystals, where the diameter may only be a few lattice constants, this isno longer the case. Therefore, it becomes an issue how small one can push theeffective mass model before it breaks.C. The FutureClearly from the discussion in Section IV. B, important problems remain to besolved before a complete theoretical understanding about the electronicstructure in nanocrystals is obtained. However, hopefully, this chapter hasalso demonstrated that we are clearly on the correct path. Further, theoreticalissues are not the only area that needs attention. More experimental dataare also necessary. Although much work has been done, it is surprising thatafter a decade of work on high-quality nanocrystal samples, detailed spectroscopicstudies have only been performed on two compound semiconductors,CdSe and InAs. Hopefully, in the coming years, this list will beexpanded. Our understanding will be truly tested only by applying it to newmaterials.ACKNOWLEDGMENTSThe author gratefully acknowledges M. G. Bawendi, Al. L. Efros, C. B.Murray, and M. Nirmal, who have greatly contributed to the results anddescriptions described in this chapter.REFERENCES1. Pankove, J.I. Optical Processes in Semiconductors; New York: Dover, 1971;34 pp.2. Efros, Al.L.; Efros, A.L. Sov. Phys. Semicond. 1982, 16, 772.3. Ekimov, A.I.; Onushchenko, A.A. JETP Lett. 1982, 34, 345.4. Brus, L.E. J. Chem. Phys. 1983, 79, 5566.5. Ekimov, A.I.; Efros, Al.L.; Onushchenko, A.A. Solid State Commun. 1985, 56,921.6. Brus, L.E. J. Chem. Phys. 1984, 80, 4403.7. Murray, C.B.; Norris, D.J.; Bawendi, M.G. J. Am. Chem. Soc. 1993, 115, 8706.8. Norris, D.J.; Sacra, A.; Murray, C.B.; Bawendi, M.G. Phys. Rev. Lett. 1994,72, 2612.9. Norris, D.J.; Bawendi, M.G. Phys. Rev. B 1996, 53, 16,338.10. Nirmal, M.; Norris, D.J.; Kuno, M.; Bawendi, M.G.; Efros, Al.L.; Rosen, M.Phys. Rev. Lett. 1995, 75, 3728.Copyright 2004 by Marcel Dekker, Inc. All Rights Reserved.
11. Norris, D.J.; Efros, Al.L.; Rosen, M.; Bawendi, M.G. Phys. Rev. B 1996,53, 16,347.12. Guzelian, A.A.; Banin, U.; Kadavanich, A.V.; Peng, X.; Alivisatos, A.P. Appl.Phys. Lett. 1996, 69, 1432.13. Banin, U.; Lee, C.J.; Guzelian, A.A.; Kadavanich, A.V.; Alivisatos, A.P.;Jaskolski, W.; Bryant, G.W.; Efros, Al.L.; Rosen, M. J. Chem. Phys. 1998, 109,2306.14. Brus, L. Appl. Phys. A 1991, 53, 465.15. Ba´nyai, L.; Koch, S.W. Semiconductor Quantum Dots. Singapore: WorldScientific, 1993.16. Alivisatos, A.P. J. Phys. Chem. 1996, 100, 13,226.17. Alivisatos, A.P. Science 1996, 271, 933.18. Woggon, U. Optical Properties of Semiconductor Quantum Dots. Heidelberg:Springer-Verlag, 1997.19. Nirmal, M.; Brus, L.E. Acc. Chem. Res. 1999, 32, 407.20. Gaponenko, S.V. Optical Properties of Semiconductor Nanocrystals. Cambridge:Cambridge University Press, 1999.21. Eychmu¨ller, A. J. Phys. Chem. B 2000, 104, 6514.22. Ashcroft, N.W.; Mermin, N.D. Solid State Physics. Orlando, FL: W.B. Saunders.23. Flu¨gge, S. Practical Quantum Mechanics. Berlin: Springer-Verlag, 1971; Vol 1,155.24. Bastard, G. Wave Mechanics Applied to Semiconductor Heterostructures. NewYork: Wiley, 1988.25. Altarelli, M. In Semiconductor Superlattices and Interfaces; Stella A, ed.Amsterdam: North-Holland, 1993; 217.26. Xia, J.B. Phys. Rev. B 1989, 40, 8500.27. Hellwege, K.H. Landolt-Bornstein Numerical Data and Functional Relationshipsin Science and Technology, New Series. Berlin: Springer-Verlag, 1982; Vol. 17b,Group III.28. Aven, M.; Prener, J.S. Physics and Chemistry of II–VI Compounds. Amsterdam:North-Holland, 1967; 41 pp.29. Kittel, C. Quantum Theory of Solids. New York: Wiley, 1987.30. Luttinger, J.M. Phys. Rev. B 1956, 102,1030.31. Luttinger, J.M.; Kohn, W. Phys. Rev. 1955, 97, 869.32. Bir, G.L.; Pikus, G.E. Symmetry and Strain-Induced Effects in Semiconductors.New York: Wiley, 1974.33. Lipari, N.O.; Baldereschi, A. Phys. Rev. Lett. 1973, 42, 1660.34. Baldereschi, A.; Lipari, N.O. Phys. Rev. B 1973, 8, 2697.35. Ge’lmont, B.L.; D’yakonov, M.I. Sov. Phys. Semicond. 1972, 5, 1905.36. Kane, E.O. J. Phys. Chem. Solids 1957, 1, 249.37. Pidgeon, C.R.; Brown, R.N. Phys. Rev. 1966, 146, 575.38. Kane, E.O. In Narrow Band Semiconductors, Physics and Applications, LectureNotes in Physics; Zawadski W, ed. Berlin: Springer-Verlag, 1980; Vol. 133.39. Vahala, K.J.; Sercel, P.C. Phys. Rev. Lett. 1990, 65, 239.40. Sercel, P.C.; Vahala, K.J. Phys. Rev. B 1990, 42, 3690.Copyright 2004 by Marcel Dekker, Inc. All Rights Reserved.
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Copyright 2004 by Marcel Dekker, In
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This book covers several topics of
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esult, some exciting topics were no
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3. Fine Structure and Polarization
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9. III-V Quantum Dots and Quantum D
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ContributorsUri BaninThe Hebrew Uni
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1‘‘Soft’’ Chemical Synthesi
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structure of energy states leads to
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growth can proceed by Ostwald ripen
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Figure 3 Transmission electron micr
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Figure 4 Temporal evolution of the
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No. 26, are f85% (Fig. 6) [21]. Alt
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tion spectra and broad PL spectra.
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ing surface-to-volume ratio with di
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Figure 8 Photoluminescence spectra
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lattice mismatch. Such a large latt
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match between InAs and ZnS of f11%.
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successfully repeated for up to thr
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Under a different growth regime, on
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Figure 14 Atomic model of the CdSe
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‘‘Teardrop-shaped’’ particl
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Figure 17 High-resolution TEMs of C
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allows isolation of tetrapods in f8
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ligand concentrations yield a reduc
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een determined and quantitatively c
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tion volumes were also shown to be
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synthesis temperatures of z400jC ar
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Figure 23 (a) Photoluminescence spe
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levels (fV1 Mn per NQD). Despite in
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Figure 25 X-ray diffraction pattern
Page 66 and 67: Figure 27 Transmission electron mic
Page 68 and 69: An additional factor that strongly
Page 70 and 71: Figure 30 (a,b) Schematics illustra
Page 72 and 73: Slow, controlled precipitation of h
Page 74 and 75: Figure 34 Schematic illustrating th
Page 76 and 77: Figure 36 Transmission electron mic
Page 78 and 79: achieving biological compatibility
Page 80 and 81: 47. Yu H.; Gibbons P.C.; Kelton K.F
Page 82 and 83: 2Electronic Structure inSemiconduct
Page 84 and 85: Figure 2 (a) Simple model of a nano
Page 88 and 89: electron and hole to be treated as
Page 90 and 91: independently, Eq. (13) is commonly
Page 92: a better description of the bulk ba
Page 95 and 96: investigated. For optical experimen
Page 97 and 98: Figure 4 (a) Absorption (solid line
Page 99 and 100: Figure 6 Normalized PLE scans for s
Page 101 and 102: Figure 8 A simplistic model for des
Page 103 and 104: Figure 10 Theoretically predicted p
Page 105 and 106: Figure 12 Schematics depicting the
Page 107 and 108: Figure 14 Calculated band-edge exci
Page 109 and 110: Figure 15 Absorption (solid line) a
Page 111 and 112: Figure 18 (a) Calculated band-edge
Page 113 and 114: IV.BEYOND CdSeA. Indium Arsenide Na
Page 115: the six-band Luttinger Hamiltonian.
Page 119 and 120: 69. Gaponenko, S.V.; Woggon, U.; Sa
Page 121 and 122: formation of a long-lived dark exci
Page 123 and 124: where the constant A is determined
Page 125 and 126: In crystals for which the function
Page 127 and 128: The respective wave functions areC
Page 129 and 130: passive, as was shown in Ref. 12. T
Page 131 and 132: square of the matrix element of the
Page 133 and 134: where e F = e F ieV and e F F = e x
Page 135 and 136: see that for all nanocrystal shapes
Page 137 and 138: optical recombination of the excito
Page 139 and 140: B. Recombination of the Dark Excito
Page 141 and 142: where x = cos h and f = l B g e H/3
Page 143 and 144: The theory of the polarization memo
Page 145 and 146: Figure 7 The size dependence of the
Page 147 and 148: state would have an infinite lifeti
Page 149 and 150: crystal axis [see Eq. (40)]. As a r
Page 151 and 152: time of the exciton momentum relaxa
Page 153 and 154: One must also account for the influ
Page 155 and 156: observed in one of the first studie
Page 157 and 158: REFERENCES1. Bawendi, M.G.; Wilson,
Page 159 and 160: 4Intraband Spectroscopyand Dynamics
Page 161 and 162: The solid line in Fig. 1 shows the
Page 163 and 164: Figure 2 FTIR spectra of n-type CdS
Page 165 and 166: of the center frequency. The experi
Page 167 and 168:
limit given by radiative relaxation
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from a long lifetime due to the pho
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are two natural approaches to study
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32. Inoshita, T.; Sakaki, H. Physic
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continuous spectral tunability over
Page 177 and 178:
function and envelope function mome
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ottleneck’’ [14,28]. Further re
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in NQDs is dominated by nonphonon e
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Figure 4 Dynamics of the IR postpum
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Figure 5 (a) Time-resolved PL spect
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Figure 6 (a) The time delay of the
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and due to Auger-type e-h interacti
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Figure 9 Dynamics of the 1S bleachi
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significantly greater than the fast
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Figure 11 (a) Pump-intensity-depend
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NQD size. For small NQD sizes (R =
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Figure 14 Nonlinear absorption/gain
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sorption change associated with a s
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where n h em is the hole ‘‘emit
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ultrafast (subpicosecond to picosec
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Figure 18 Schematic of transitions
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Figure 19 Dynamics of pump-induced
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where n i (i=1, 2 . . . , N ) is th
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Figure 21 (a) Two-e-h-pair (biexcit
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the volume fraction (filling factor
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intensity dependence of this peak (
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Page 221 and 222:
can contribute to the saturation of
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coupling between ‘‘volume’’
Page 227 and 228:
numerous discussions on the photoph
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53. Kang, K.; Kepner, A.; Gaponenko
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the ‘‘on-off ’’ emission in
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parallel form of data acquisition i
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Figure 3 (a) Spectral time trace of
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transition energies. In fact, these
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distribution (dark line) does not d
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exposure to only room light. In our
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statistics for the off times are in
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230Shimizu and BawendiCopyright 200
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Figure 10 (a) Time trace of a CdSe(
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and excited QD core states to fluct
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arrows indicate the on-time truncat
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W. K. Woo and V. C. Sundar for assi
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size allows the electron affinity a
Page 257 and 258:
II.THEORY OF ELECTRON TRANSFER BETW
Page 259 and 260:
For the specific case of charge tra
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dominates, the mobility is often fi
Page 263 and 264:
where the constant A and the temper
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components of modulation which are
Page 267 and 268:
nanocrystals [41], understanding ph
Page 269 and 270:
and ionization potential through tw
Page 271 and 272:
quantum dots. Furthermore, because
Page 273 and 274:
For many applications, a host mater
Page 275 and 276:
form blends with morphologies that
Page 277 and 278:
Figure 11 Photoluminescence efficie
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Figure 12 (a) Room-temperature PIA
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discussed briefly in Section IV. Ch
Page 283 and 284:
dithiolates to thiol-terminated DNA
Page 285 and 286:
Films of passivated CdSe nanocrysta
Page 287 and 288:
Figure 16 Photocurrent action spect
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decay with stretched exponential ki
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siderably larger than might be esti
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dispersing CdSe nanocrystal chromop
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memory and charge storage effects [
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all) of the optically excited elect
Page 299 and 300:
composites of nanocrystals and conj
Page 301 and 302:
55. Asbury, J.B.; Hao, E.C.; Wang,
Page 303 and 304:
108. Morgan, N.Y.; Leatherdale, C.A
Page 305 and 306:
The approaches to fabrication of se
Page 307 and 308:
Figure 1 Experimental realization o
Page 309 and 310:
Due to this voltage division, the m
Page 311 and 312:
Figure 3 Simulated tunneling spectr
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electron charging. In both positive
Page 315 and 316:
Figure 5 shows the typical features
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Figure 7 Map of levels for InAs nan
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Figure 8 Scanning electron microsco
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D CB = 0.31 eV is thus obtained. On
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Figure 11 Correlation of optical an
Page 325 and 326:
atomistic approach based on pseudop
Page 327 and 328:
charging indicated that the tunneli
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capacitance values were also kept t
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could not be detected in the QD/DT/
Page 333 and 334:
Figure 18 Tunneling conductanceF sp
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data in the inset of Fig. 19 repres
Page 337 and 338:
corresponding to the s-like wave fu
Page 339 and 340:
7. Grabert, H.; Devoret, M.H., Eds.
Page 341 and 342:
66. Su, B.; Goldman, V.J.; Cunningh
Page 343 and 344:
dimensional confinement are created
Page 345 and 346:
Figure 1 Transmission electron micr
Page 347 and 348:
The room-temperature absorption and
Page 349 and 350:
narrower in samples with larger mea
Page 351 and 352:
GaInP 2 QDs from a plot of the squa
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crystal, indicating lattice-matched
Page 355 and 356:
Figure 5 Evolution of Stranski-Kras
Page 357 and 358:
Page 359 and 360:
Page 361 and 362:
C. Efficient Anti-Stokes Photolumin
Page 363 and 364:
Because HF treatment has been shown
Page 365 and 366:
Page 367 and 368:
intensity of the PL when it is on a
Page 369 and 370:
eV stems from recombining carriers
Page 371 and 372:
Figure 16 Model to explain two-colo
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although this term is not rigorousl
Page 375 and 376:
10 ps (about an order of magnitude
Page 377 and 378:
electron relaxation is inhibited an
Page 379 and 380:
Figure 18 Transmission electron mic
Page 381 and 382:
QDs, the nature of the QD capping s
Page 383 and 384:
QD solution. For an interdot distan
Page 385 and 386:
emission spectra of the two individ
Page 387 and 388:
Figure 23 Change of the PL intensit
Page 389 and 390:
(viz. the absorbed light intensity)
Page 391 and 392:
Figure 25Impact ionization in QDs.m
Page 393 and 394:
prevent electron-hole recombination
Page 395 and 396:
36. Miller, R.D.J.; McLendon, G.; N
Page 397 and 398:
91. Vurgaftman, I.; Singh, J. Appl.
Page 399 and 400:
139. Mićić, O.I.; Ahrenkiel, S.P.
Page 401 and 402:
10Synthesis and Fabrication of Meta
Page 403 and 404:
Figure 2 (A-C) Progression of HR-TE
Page 405 and 406:
Figure 3 Schematic for gold nanocry
Page 407 and 408:
Nanocrystal growth can occur by two
Page 409 and 410:
on the other hand, provide an ensem
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Figure 6 (a) SAXS patterns for disp
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Figure 8 The gold nanocrystal film
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of the stabilizing ligand, and the
Page 417 and 418:
successfully modeled the 2D island
Page 419 and 420:
2. Steric Stabilization and a Soft
Page 421 and 422:
are fully extended. Moving away fro
Page 423 and 424:
Figure 11 High-resolution SEM image
Page 425 and 426:
Figure 13 (A) Transmission electron
Page 427 and 428:
function of the density of localize
Page 429 and 430:
Figure 15 High-resolution SEM image
Page 431 and 432:
thiol-capped nanocrystals [2]. The
Page 433 and 434:
41. Ackerson, B.J. Nature 1993, 365
Page 435 and 436:
with the effect of the particle com
Page 437 and 438:
Figure 1a shows the surface plasmon
Page 439 and 440:
Figure 2 (a) Ultraviolet-visible ab
Page 441 and 442:
agents [34]. The short-wavelength b
Page 443 and 444:
Figure 4 (a) Plot of the plasmon ab
Page 445 and 446:
the framework of traditional Mie’
Page 447 and 448:
show that effects due to the surrou
Page 449 and 450:
is located at the position of the g
Page 451 and 452:
Page 453 and 454:
Figure 8 Ultraviolet-visible absorp
Page 455 and 456:
laser pulses while being mixed in t
Page 457 and 458:
Figure 10 shows HR-TEM images of go
Page 459 and 460:
Figure 11 Transmission electron mic
Page 461 and 462:
final irradiation product. At the s
Page 463 and 464:
following the laser excitation appe
Page 465 and 466:
36. Papavassiliou, G.C. Prog. Solid
Page 467 and 468:
particles to expand. Because the he
Page 469 and 470:
was frequency doubled in a 1-mm B-
Page 471 and 472:
Figure 2 Frequency of the acoustic
Page 473 and 474:
Figure 3 Change in radius (DR/R) ve
Page 475 and 476:
In this model, the electrons couple
Page 477 and 478:
Figure 5 Transient bleach data for
Page 479 and 480:
Figure 7 (a) Transient bleach data
Page 481 and 482:
that the particles with >80% Au hav
Page 483 and 484:
3. Del Fatti, N.; Valle´e, F.; Fly
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