SpringerLink
Log in

Defects in Amorphous and Organic Semiconductors

  • Reference work entry
  • First Online:
Semiconductor Physics

  • 2338 Accesses

Abstract

Amorphous and organic semiconductors have strong topological irregularities with respect to specific ideal structures, which depend on the particular class of such semiconductors. Most of these defects are rather gradual displacements from an ideal surrounding. The disorder leads to defects levels with a broad energy distribution which extends as band tails into the bandgap. Instead of a sharp band edge known from crystalline solids a mobility edge exists separating between extended states in the bands and localized states in the band tails.

Amorphous semiconductors, also referred to as semiconducting glasses, comprise the classes of amorphous chalcogenides and tetrahedrally bonded amorphous semiconductors. Amorphous chalcogenides are structurally floppy solids with low average coordination numbers and pronounced pinning of the Fermi level near midgap energy. The more rigid tetrahedrally bonded amorphous semiconductors have larger coordination numbers. They may be well doped p-type and n-type much like crystalline semiconductors.

Organic semiconductors comprise small-molecule crystals and polymers. Both have weak intermolecular bonds favoring deviations from ideal alignment. In small-molecule semiconductors the structure of thin films grown on substrates usually deviates from the structure of bulk crystals, with a substantially different molecule ordering at the interface and a strong dependence on the dielectric properties of the substrate. Polymers consist of long chain-like molecules packed largely uniformly in crystalline domains separated by amorphous regions with tangled polymer chains. Besides chemical structure of the chains crystallinity depends on the molecular length.

Karl W. Böer: deceased.

This is a preview of subscription content, log in via an institution to check access.

Access this chapter

Log in via an institution

Subscribe and save

Springer+ Basic
EUR 32.99 /Month
  • Get 10 units per month
  • Download Article/Chapter or Ebook
  • 1 Unit = 1 Article or 1 Chapter
  • Cancel anytime
Subscribe now

Buy Now

Chapter
EUR 29.95
Price includes VAT (Germany)
  • Available as PDF
  • Read on any device
  • Instant download
  • Own it forever
eBook
EUR 855.99
Price includes VAT (Germany)
  • Available as EPUB and PDF
  • Read on any device
  • Instant download
  • Own it forever
Hardcover Book
EUR 962.99
Price includes VAT (Germany)
  • Durable hardcover edition
  • Dispatched in 3 to 5 business days
  • Free ship** worldwide - see info

Tax calculation will be finalised at checkout

Purchases are for personal use only

Institutional subscriptions

Similar content being viewed by others

Notes

  1. 1.

    In amorphous structures the average number of next neighbors may substantially differ from that of the corresponding crystalline counterpart, see Sect. 3.1 of Chap. 3, “The Structure of Semiconductors”.

  2. 2.

    It should be noted that the definition of a band state is related to the coherence length of an electron wave, which is essentially the same as the mean free path λ.

  3. 3.

    A third class, somewhat in between these two, contains α-P and α-As.

  4. 4.

    Bipolar devices made from such materials are capable of switching at high speed from a low to a high conducting state at a critical bias (Ovshinsky 1968).

  5. 5.

    Polycyclic aromatic hydrocarbons like pentacene have a positively charged planar backbone of atom cores and negatively charged π electrons in front and at the back of this plane, yielding a permanent quadrupole moment.

  6. 6.

    More than a single g parameter, referring to different hkl directions and related fluctuations, may be required to characterize a sample. Also a description in terms of a g parameter accounting for the lattice disorder within paracrystals and another parameter for the degree of paracrystallinity, which measures the mass/volume fraction of ordered material as discussed by Marina et al. (2022), may be convenient.

  7. 7.

    The repetition unit of fused-ring polythiophene comprises four rings like those shown in Fig. 15a with the inner two rings fused by commonly sharing a two carbon atoms with a C = C double bond (see inset Fig. 16).

References

  • Abtew TA, Drabold DA (2006) Atomistic simulation of light-induced changes in hydrogenated amorphous silicon. J Phys Condens Matter 18:L1

    ADS  Google Scholar 

  • Adler D (1985) Chemistry and physics of covalent amorphous semiconductors. In: Adler D, Schwartz BB, Steele MC (eds) Physical properties of amorphous materials. Plenum Press, New York, pp 1–103

    Google Scholar 

  • Adler D, Fritzsche H (eds) (1985) Tetrahedrally bonded amorphous semiconductors. Springer, New York

    Google Scholar 

  • Adler D, Yoffa EJ (1977) Localized electronic states in amorphous semiconductors. Can J Chem 55:1920

    Google Scholar 

  • Al-Mahboob A, Sadowski JT, Fujikawa Y, Nakajima K, Sakurai T (2008) Kinetics-driven anisotropic growth of pentacene thin films. Phys Rev B 77:035426

    ADS  Google Scholar 

  • Anderson PW (1958) Absence of diffusion in certain random lattices. Phys Rev 109:1492

    ADS  Google Scholar 

  • Anderson PW (1975) Model for the electronic structure of amorphous semiconductors. Phys Rev Lett 34:953

    ADS  Google Scholar 

  • Chen S, Li Z, Qiao Y, Song Y (2021) Solution-processed organic semiconductor crystals for field-effect transistors: from crystallization mechanism towards morphology control. J Mater Chem C 9:1126

    Google Scholar 

  • Cohen MH, Fritzsche H, Ovshinsky SR (1969) Simple band model for amorphous semiconducting alloys. Phys Rev Lett 22:1065

    ADS  Google Scholar 

  • Dinca LE, De Marchi F, MacLeod JM, Lipton-Duffin J, Gatti R, Ma D, Perepichkab DF, Rosei F (2015) Pentacene on Ni(111): room-temperature molecular packing and temperature-activated conversion to graphene. Nanoscale 7:3263

    ADS  Google Scholar 

  • Djordjevic BR, Thorpe MF, Wooten F (1995) Computer model of tetrahedral amorphous diamond. Phys Rev B 52:5685

    ADS  Google Scholar 

  • Drabold DA, Nakhmanson S, Zhang X (2001) Electronic structure of amorphous insulators and phoro-structural effects in chalcogenide glasses. In: Thorpe MF, Tichý L (eds) Properties and applications of amorphous materials. Kluwer, Dordrecht, pp 221–250

    Google Scholar 

  • Evans PG, Spalenka JW (2015) Epitaxy of small organic molecules. In: Kuech TF (ed) Handbook of crystal growth of thin films and epitaxy: basic techniques, vol 3 part A, 2nd edn. Elsevier, Amsterdam, pp 509–554

    Google Scholar 

  • Forrest SR (1997) Ultrathin organic films grown by organic molecular beam deposition and related techniques. Chem Rev 97:1793

    Google Scholar 

  • Fugallo G, Mattoni A (2014) Thermally induced recrystallization of textured hydrogenated nanocrystalline silicon. Phys Rev B 89:045301

    ADS  Google Scholar 

  • Götze W (1981) The conductor-nonconductor transition in strongly disordered three-dimensional systems. In: Devreese JT (ed) Recent development in condensed matter physics. Plenum Press, New York, pp 133–154

    Google Scholar 

  • Götzen J, Käfer D, Wöll C, Witte G (2010) Growth and structure of pentacene films on graphite: weak adhesion as a key for epitaxial film growth. Phys Rev B 81:085440

    ADS  Google Scholar 

  • Hamers RJ (2008) Formation and characterization of organic monolayers on semiconductor surfaces. Annu Rev Anal Chem 1:707

    Google Scholar 

  • Hillier AC, Ward MD (1996) Epitaxial interactions between molecular overlayers and ordered substrates. Phys Rev B 54:14037

    ADS  Google Scholar 

  • Hindeleh AM, Hosemann R (1988) Paracrystals representing the physical state of matter. J Phys C 21:4155

    ADS  Google Scholar 

  • Hindeleh AM, Hosemann R (1991) Microparacrystals: the intermediate stage between crystalline and amorphous. J Mater Sci 26:5127

    ADS  Google Scholar 

  • Hooks DE, Fritz T, Ward MD (2001) Epitaxy and molecular organization on solid substrates. Adv Mater 13:227

    Google Scholar 

  • Hosemann R, Hindeleh AM (1995) Structure of crystalline and paracrystalline condensed matter. J Macromol Sci Phys B 34:327

    Google Scholar 

  • Hosono H (2006) Ionic amorphous oxide semiconductors: material design, carrier transport, and device application. J Non-Cryst Sol 352:851

    ADS  Google Scholar 

  • Huang B, Robertson J (2012) Nature of defects and gap states in GeTe model phase change materials. Phys Rev B 85:125305

    ADS  Google Scholar 

  • Hudgens S (2012) Progress in understanding the Ovshinsky Effect: Threshold switching in chalcogenide amorphous semiconductors. Phys Stat Sol B 249:1951

    ADS  Google Scholar 

  • Jarolimek K, de Groot RA, de Wijs GA, Zeman M (2009) First-principles study of hydrogenated amorphous silicon. Phys Rev B 79:155206

    ADS  Google Scholar 

  • Jia S, Li H, Gotoh T, Longeaud C, Zhang B, Lyu J, Lv S, Zhu M, Song Z, Liu Q, Robertson J, Liu M (2020) Ultrahigh drive current and large selectivity in GeS selector. Nat Commun 11:4636

    ADS  Google Scholar 

  • Käfer D, Ruppel L, Witte G (2007) Growth of pentacene on clean and modified gold surfaces. Phys Rev B 75:085309

    ADS  Google Scholar 

  • Kalb WL, Mattenberger K, Batlogg B (2008) Oxygen-related traps in pentacene thin films: energetic position and implications for transistor performance. Phys Rev B 78:035334

    ADS  Google Scholar 

  • Kalb WL, Haas S, Krellner C, Mathis T, Batlogg B (2010) Trap density of states in small-molecule organic semiconductors: a quantitative comparison of thin-film transistors with single crystals. Phys Rev B 81:155315

    ADS  Google Scholar 

  • Kang JH, da Silva Filho D, Bredas J-L, Zhu X-Y (2005) Shallow trap states in pentacene thin films from molecular sliding. Appl Phys Lett 86:152115

    ADS  Google Scholar 

  • Kastner M, Adler D, Fritzsche H (1976) Valence-alternation model for localized gap states in lone-pair semiconductors. Phys Rev Lett 37:1504

    ADS  Google Scholar 

  • Knights JC, Biegelsen DK, Solomon I (1977) Optically induced electron spin resonance in doped amorphous silicon. Solid State Commun 22:133

    ADS  Google Scholar 

  • Knipp D, Northrup JE (2009) Electric-field-induced gap states in pentacene. Adv Mater 21:2511

    Google Scholar 

  • Koch FPV, Rivnay J, Foster S, Müller C, Downing JM, Buchaca-Domingo E, Westacott P, Yu L, Yuan M, Baklar M, Fei Z, Luscombe C, McLachlan MA, Heeney M, Rumbles G, Silva C, Salleo A, Nelson J, Smith P, Stingelin N (2013) The impact of molecular weight on microstructure and charge transport in semicrystalline polymer semiconductors–poly(3-hexylthiophene), a model study. Prog Polym Sci 38:1978

    Google Scholar 

  • Lang DV, Chi X, Siegrist T, Sergent AM, Ramirez AP (2004) Amorphouslike density of gap states in single-crystal pentacene. Phys Rev Lett 93:086802

    ADS  Google Scholar 

  • LeComber PG, Spear WE (1976) Electronic properties of doped amorphous Si and Ge. Am Inst Phys Conf Proc 31:284

    ADS  Google Scholar 

  • Lee PA, Ramakrishna TV (1985) Disordered electronic systems. Rev Mod Phys 57:287

    ADS  Google Scholar 

  • Lewis LJ, Mousseau N (1998) Tight-binding molecular-dynamics studies of defects and disorder in covalently bonded materials. Comput Mater Sci 12:210

    Google Scholar 

  • Li JM, Pfeiffer G, Paesler MA, Sayers DE, Fontaine A (1989) Photon intensity-dependent darkening kinetics in optical and structural anisotropy in a-As2S3: a study of X-ray absorption spectroscopy. J Non Cryst Solids 114:52

    ADS  Google Scholar 

  • Lietoila A, Wakita A, Sigmon TW, Gibbons JF (1982) Epitaxial regrowth of intrinsic, p-doped and compensated (P + B-doped) amorphous Si. J Appl Phys 53:4399

    ADS  Google Scholar 

  • Lifshitz IM (1964) The energy spectrum of disordered systems. Adv Phys 13:483

    ADS  MATH  Google Scholar 

  • Maeda T, Kobayashi T, Nemoto T, Isoda S (2001) Lattice defects in organic crystals revealed by direct molecular imaging. Philos Mag B 81:1659

    ADS  Google Scholar 

  • Mannsfeld SCB, Virkar A, Reese C, Toney MF, Bao Z (2009) Precise structure of pentacene monolayers on amorphous silicon oxide and relation to charge transport. Adv Mater 21:2294

    Google Scholar 

  • Marina S, Gutierrez-Fernandez E, Gutierrez J, Gobbi M, Ramos N, Solano E, Rech J, You W, Hueso L, Tercjak A, Ade H, Martin J (2022) Semi-paracrystallinity in semi-conducting polymers. Mater Horiz 9:1196

    Google Scholar 

  • Mattheus CC, Baas J, Meetsma A, de Boer JL, Kloc C, Siegrist T, Palstra TTM (2002) A 2:1 cocrystal of 6,13-dihydropentacene and pentacene. Acta Crystallogr E 58:o1229

    Google Scholar 

  • Meidanshahi RV, Bowden S, Goodnick SM (2019) Electronic structure and localized states in amorphous Si and hydrogenated amorphous Si. Phys Chem Chem Phys 21:13248

    Google Scholar 

  • Meyer zu Heringdorf F-J, Reuter MC, Tromp RM (2001) Growth dynamics of pentacene thin films. Nature 412:517

    ADS  Google Scholar 

  • Mosley LE, Paesler MA (1984) Electronic effect on crystallization growth velocities produced by charged dangling bonds in a-Si. Appl Phys Lett 45:86

    ADS  Google Scholar 

  • Mott NF (1969) Charge transport in non-crystalline semiconductors. In: Madelung O (ed) Festkörperprobleme/Advances in solid state physics, vol 9. Vieweg, Braunschweig, pp 22–45

    Google Scholar 

  • Mott NF, Davis EA (1979) Electronic processes in non-crystalline materials, 2nd edn. Oxford University Press, Oxford, UK

    Google Scholar 

  • Mott NF, Massey HSW (1965) The theory of atomic collisions. Claredon Press, Oxford, UK

    MATH  Google Scholar 

  • Mousseau N, Barkema GT (2000) Activated mechanisms in amorphous silicon: an activation-relaxation-technique study. Phys Rev B 61:1898

    ADS  Google Scholar 

  • Northrup JE (2015) Mobility enhancement in polymer organic semiconductors arising from increased interconnectivity at the level of polymer segments. Appl Phys Lett 106:023303

    ADS  Google Scholar 

  • Northrup JE, Chabinyc ML (2003) Gap states in organic semiconductors: hydrogen- and oxygen-induced states in pentacene. Phys Rev B 68:041202

    ADS  Google Scholar 

  • Orapunt F, O’Leary SK (2008) Optical transitions and the mobility edge in amorphous semiconductors: A joint density of states analysis. J Appl Phys 104:073513

    ADS  Google Scholar 

  • Ovshinsky SR (1968) Reversible electrical switching phenomena in disordered structures. Phys Rev Lett 21:1450

    ADS  Google Scholar 

  • Ovshinsky SR (1976) Localized states in the gap of amorphous semiconductors. Phys Rev Lett 36:1469

    ADS  Google Scholar 

  • Ovshinsky SR (1977) Chemical modification of amorphous chalcogenides. In: Proceedings of the 7th international conference on amorphous and liquid semiconductors, Edinburgh, pp 519–523

    Google Scholar 

  • Ovshinsky SR (1980) The chemistry of glassy materials and their relevance to energy conversion. J Non Cryst Solids 42:335

    ADS  Google Scholar 

  • Pantelides ST (1986) Defects in amorphous silicon: a new perspective. Phys Rev Lett 57:2979

    ADS  Google Scholar 

  • Pantelides ST (1989) The nature of defects and defect dynamics in amorphous silicon. In: Fritzsche H (ed) Amorphous silicon and related materials. World Scientific Publishing, New York, pp 541–556

    Google Scholar 

  • Park B-N, Seo S, Evans P (2007) Channel formation in single-monolayer pentacene thin film transistors. J Phys D 40:3506

    ADS  Google Scholar 

  • Peng Z, Ye L, Ade H (2022) Understanding, quantifying, and controlling the molecular ordering of semiconducting polymers: from novices to experts and amorphous to perfect crystals. Mater Horiz 9:577

    Google Scholar 

  • Pfanner G, Freysoldt C, Neugebauer J, Inam F, Drabold D, Jarolimek K, Zeman M (2013) Dangling-bond defect in a-Si:H: characterization of network and strain effects by first-principles calculation of the EPR parameters. Phys Rev B 87:125308

    ADS  Google Scholar 

  • Prasai K, Biswas P, Drabold DA (2016) Electrons and phonons in amorphous semiconductors. Semicond Sci Technol 31:073002

    ADS  Google Scholar 

  • Rivnay J, Noriega R, Northrup JE, Kline RJ, Toney MF, Salleo A (2011) Structural origin of gap states in semicrystalline polymers and the implications for charge transport. Phys Rev B 83:121306

    ADS  Google Scholar 

  • Robertson J (2012) Properties and do** limits of amorphous oxide semiconductors. J Non-Cryst Sol 358:2437

    ADS  Google Scholar 

  • Sanchez ML, Aguilar MA, de Valle FJO (1997) Study of solvent effects by means of averaged solvent electrostatic potentials obtained from molecular dynamics data. J Comput Chem 18:313

    Google Scholar 

  • Seo S, Evans PG (2009) Molecular structure of extended defects in monolayer-scale pentacene thin films. J Appl Phys 106:103521

    ADS  Google Scholar 

  • Simbrunner C, Sitter H (2015) Organic van der Waals epitaxy versus templated growth by organic-organic heteroepitaxy. In: Kuech TF (ed) Handbook of crystal growth of thin films and epitaxy: basic techniques, vol 3 part A, 2nd edn. Elsevier, Amsterdam, pp 483–508

    Google Scholar 

  • Staebler DL, Wronski CR (1977) Reversible conductivity changes in discharge-produced amorphous Si. Appl Phys Lett 31:292

    ADS  Google Scholar 

  • Street RA (1991) Hydrogenated amorphous silicon. Cambridge University Press, Cambridge, UK

    Google Scholar 

  • Street RA, Mott NF (1975) States in the gap in glassy semiconductors. Phys Rev Lett 35:1293

    ADS  Google Scholar 

  • Street RA, Northrup JE, Salleo A (2005) Transport in polycrystalline polymer thin-film transistors. Phys Rev B 71:165202

    ADS  Google Scholar 

  • Stuke J (1976) In: Kolomiets BT (ed) Electronic phenomena in non-crystalline solids. USSR Academy of Sciences, Leningrad, pp 193–202

    Google Scholar 

  • Tanaka K (1998) Medium-range structure in chalcogenide glasses. Jpn J Appl Phys 37:1747

    ADS  Google Scholar 

  • Tanaka K, Nakayama S-i (1999) Band-tail characteristics in amorphous semiconductors studied by the constant-photocurrent method. Jpn J Appl Phys 38:3986

    ADS  Google Scholar 

  • Thouless DJ (1974) Electrons in disordered systems and the theory of localization. Phys Rep 13:93

    ADS  Google Scholar 

  • Tsetseris L, Pantelides ST (2007) Intercalation of oxygen and water molecules in pentacene crystals: first-principles calculations. Phys Rev B 75:153202

    ADS  Google Scholar 

  • Varshishta P, Kalia RK, Nakano A, Li W, Ebbsjö I (1996) Molecular dynamics methods and large-scale simulations of amorphous materials. In: Thorpe MF, Mitkova MI (eds) Amorphous insulators and semiconductors. NATO ASI ser 3 high technology, vol 23. Kluwer Academic Publishers, Dordrecht, p 151

    Google Scholar 

  • Varshneya AK, Seeram AN, Swiler DR (1993) A review of the average coordination number concept in multicomponent chalcogenide glass systems. Phys Chem Glasses 34:179

    Google Scholar 

  • Verlaak S, Heremans P (2007) Molecular microelectrostatic view on electronic states near pentacene grain boundaries. Phys Rev B 75:115127

    ADS  Google Scholar 

  • Virkar AA, Mannsfeld S, Bao Z, Stingelin N (2010) Organic semiconductor growth and morphology considerations for organic thin-film transistor. Adv Mater 22:3857

    Google Scholar 

  • Wooten F, Weaire D (1989) Modelling tetrahedrally bonded random networks by computer. In: Ehrenreich H, Turnbull D (eds) Solid state physics, vol 40. Academic Press, New York, pp 1–42

    Google Scholar 

  • Yogev S, Matsubara R, Nakamura M, Zschieschang U, Klauk H, Rosenwaks Y (2013) Fermi level pinning by gap states in organic semiconductors. Phys Rev Lett 110:036803

    ADS  Google Scholar 

  • Wuttig M, Yamada N (2007) Phase-change materials for rewriteable data storage. Nat Mater 6:824

    ADS  Google Scholar 

  • Zipoli F, Krebs D, Curioni A (2016) Structural origin of resistance drift in amorphous GeTe. Phys Rev B 93:115201

    ADS  Google Scholar 

Download references

Author information

Authors and Affiliations

  1. Institut für Festkörperphysik, EW5-1, Technische Universität Berlin, Berlin, Germany

    Udo W. Pohl

Authors
  1. Karl W. Böer
    View author publications

    You can also search for this author in PubMed Google Scholar

  2. Udo W. Pohl
    View author publications

    You can also search for this author in PubMed Google Scholar

Corresponding author

Correspondence to Udo W. Pohl .

Rights and permissions

Reprints and permissions

Copyright information

© 2023 Springer Nature Switzerland AG

About this entry

Check for updates. Verify currency and authenticity via CrossMark

Cite this entry

Böer, K.W., Pohl, U.W. (2023). Defects in Amorphous and Organic Semiconductors. In: Semiconductor Physics. Springer, Cham. https://doi.org/10.1007/978-3-031-18286-0_20

Download citation

Publish with us

Policies and ethics

Search

Navigation