Journal of Nanoparticle Research

, Volume 13, Issue 1, pp 221–232 | Cite as

Structural investigations of Ge nanoparticles embedded in an amorphous SiO2 matrix

  • Ionel Stavarache
  • Ana-Maria Lepadatu
  • Nicoleta G. Gheorghe
  • Ruxandra M. Costescu
  • George E. Stan
  • Dan Marcov
  • Adrian Slav
  • Gheorghe Iordache
  • Tionica F. Stoica
  • Vladimir Iancu
  • Valentin S. Teodorescu
  • Cristian M. Teodorescu
  • Magdalena Lidia Ciurea
Research Paper

Abstract

Transmission electron microscopy and X-ray photoelectron spectroscopy analyses are performed to investigate Ge nanoparticles embedded in an amorphous SiO2 matrix. GeSiO thin films are prepared by two methods, sol–gel and radio frequency magnetron sputtering. After the deposition, the sol–gel films are annealed in either N2 (at 1 atm and 800 °C) or H2 (at 2 atm and 500 °C), and the sputtered films in H2 (at 2 atm and 500 °C), to allow Ge segregation. Amorphous Ge-rich nanoparticles (3–7 nm size) are observed in sol–gel films. Crystalline Ge nanoparticles in the high pressure tetragonal phase (10–50 nm size) are identified in the sputtered films. The size of the nanoparticles increases with Ge concentration in the volume of the film. At the film surface, the Ge concentration is much larger that in the volume for both sol–gel and sputtered films. At the same time, at the film surface, only oxidized Ge is observed.

Keywords

Nanoparticles Sol–gel Magnetron sputtering TEM XPS Composite nanomaterials 

References

  1. Allen LC (1989) Electronegativity is the average one-electron energy of the valence-shell electrons in ground-state free atoms. J Am Chem Soc 111:9003–9014. doi:10.1021/ja00207a003 CrossRefGoogle Scholar
  2. Atzrodt V, Wirth T, Lange H (1980) Investigation of NiSi and Pd3Si thin films by AES and XPS. Phys Status Solidi A 62:531–537. doi:10.1002/pssa.2210620222 CrossRefGoogle Scholar
  3. Basa P, Alagoz AS, Lohner T, Kulakci M, Turan R, Nagy K, Horváth ZsJ (2008) Electrical and ellipsometry study of sputtered SiO2 structures with embedded Ge nanocrystals. Appl Surf Sci 254:3626–3629. doi:10.1016/j.apsusc.2007.10.075 CrossRefGoogle Scholar
  4. Bearden JA, Burr AF (1967) Reevaluation of X-ray atomic energy levels. Rev Mod Phys 39:125–142. doi:10.1103/RevModPhys.39.125 CrossRefGoogle Scholar
  5. Brenier R, Urlacher C, Mugnier J, Brunel M (1999) Stress development in amorphous zirconium oxide films prepared by sol–gel processing. Thin Solid Films 338:136–141. doi:10.1016/S0040-6090(98)01092-X CrossRefGoogle Scholar
  6. Ciurea ML, Teodorescu VS, Iancu V, Balberg I (2006) Electronic transport in Si–SiO2 nanocomposite films. Chem Phys Lett 423:225–228. doi:10.1016/j.cplett.2006.03.070 CrossRefGoogle Scholar
  7. Clarke TA, Rizkalla EN (1976) X-ray photoelectron spectroscopy of some silicates. Chem Phys Lett 37:523–526. doi:10.1016/0009-2614(76)85029-4 CrossRefGoogle Scholar
  8. Conibeer G, Green M, Corkish R, Cho Y, Cho EC, Jiang CW, Fangsuwannarak T, Pink E, Huang YD, Puzzer T, Trupke T, Richards B, Shalav A, Lin KL (2006) Silicon nanostructures for third generation photovoltaic solar cells. Thin Solid Films 511–512:654–662. doi:10.1016/j.tsf.2005.12.119 CrossRefGoogle Scholar
  9. Das K, NandaGoswami M, Mahapatra R, Kar GS, Dhar A, Acharya HN, Maikap S, Lee J-H, Ray SK (2004) Charge storage and photoluminescence characteristics of silicon oxide embedded Ge nanocrystal trilayer structures. Appl Phys Lett 84:1386–1388. doi:10.1063/1.1646750 CrossRefGoogle Scholar
  10. Desnica UV, Salamon K, Buljan M, Dubcek P, Radic N, Desnica-Frankovic ID, Siketic Z, Bogdanovic-Radovic I, Ivanda M, Bernstorff S (2008) Formation of Ge-nanocrystals in SiO2 matrix by magnetron sputtering and post-deposition thermal treatment. Superlattices Microstruct 44:323–330. doi:10.1016/j.spmi.2008.01.021 CrossRefGoogle Scholar
  11. Duguay S, Grob JJ, Slaoui A, Le Gall Y , Amann-Liess M (2005) Structural and electrical properties of Ge nanocrystals embedded in SiO2 by ion implantation and annealing. J Appl Phys 97(104330):1–5. doi:10.1063/1.1909286 Google Scholar
  12. Gacem K, El Hdiy A, Troyon M, Berbezier I, Szkutnik PD, Karmous A, Ronda A (2007) Memory and Coulomb blockade effects in germanium nanocrystals embedded in amorphous silicon on silicon dioxide. J Appl Phys 102(093704):1–4. doi:10.1063/1.2804013 Google Scholar
  13. Gao F, Green MA, Conibeer G, Cho EC, Huang YD, Pere-Wurfl I, Flynn C (2008) Fabrication of multilayered Ge nanocrystals by magnetron sputtering and annealing. Nanotechnology 19(455611):1–5. doi:10.1088/0957-4484/19/45/455611 Google Scholar
  14. Heitmann J, Müller F, Yi LX, Zacharias M, Kovalev D, Eichhorn F (2004) Confinement and migration effects: excitons in Si nanocrystals. Phys Rev B 69(195309):1–7. doi:10.1103/PhysRevB.69.195309 Google Scholar
  15. Heng CL, Teo NW, Ho V, Tay MS, Lei Y, Choi WK, Chim WK (2003) Effects of rapid thermal annealing time and ambient temperature on the charge storage capability of SiO2/pure Ge/rapid thermal oxide memory structure. Microelectron Eng 66:218–223. doi:10.1016/S0167-9317(03)00050-9 CrossRefGoogle Scholar
  16. Heng CL, Tjiu WW, Finstad TG (2004) Charge-storage effects in a metal-insulator semiconductor structure containing germanium nano-crystals formed by rapid thermal annealing of an electron-beam evaporated germanium layer. Appl Phys A 78:1181–1186. doi:10.1007/s00339-003-2482-0 CrossRefGoogle Scholar
  17. Hollinger G (1981) Structures chimique et electronique de l’interface SiO2–Si. Appl Surf Sci 8:318–336. doi:10.1016/0378-5963(81)90126-4 CrossRefGoogle Scholar
  18. Hong SH, Kim MC, Jeong PS, Choi SH, Kim KJ (2008) Ge-nanodot multilayer nonvolatile memories, Nanotechnology 19(305203):1–4. doi:10.1088/0957-4484/19/30/305203 Google Scholar
  19. Hüffner S (2003) Photoelectron spectroscopy: principles and applications. Springer-Verlag, Berlin, 3rd revised and enlarged edition, XV, 662 p. 461 illus., Hardcover. ISBN: 978-3-540-41802-3Google Scholar
  20. Kanjilal A, Lundsgaard Hansen J, Gaiduk P, Nylandsted Larsen A, Cherkashin N, Claverie A, Normand P, Kapelanakis E, Skarlatos D, Tsoukalas D (2003) Structural and electrical properties of silicon dioxide layers with embedded germanium nanocrystals grown by molecular beam epitaxy. Appl Phys Lett 82:1212–1214. doi:10.1063/1.1555709 CrossRefGoogle Scholar
  21. Kanoun M, Souifi A, Baron T, Mazen F (2004) Electrical study of Ge-nanocrystal-based metal-oxide-semiconductor structures for p-type nonvolatile memory applications. Appl Phys Lett 84:5079–5081. doi:10.1063/1.1751227 CrossRefGoogle Scholar
  22. Kerkhof FPJ, Moulijn JA, Heeres A (1978) The XPS spectra of the metathesis catalyst tungsten oxide on silica gel. J Electron Spectrosc Relat Phenom. 14:453–466. doi:10.1016/0368-2048(78)87004-2
  23. Kovalev D, Heckler H, Ben-Chorin M, Polisski G, Schwartzkopff M, Koch F (1998) Breakdown of the k-conservation rule in Si nanocrystals. Phys Rev Lett 81:2803–2806. doi:10.1103/PhysRevLett.81.2803 CrossRefGoogle Scholar
  24. Luca D, Macovei D, Teodorescu CM (2006) Characterization of titania thin films prepared by reactive pulsed-laser ablation. Surf Sci 600:4342–4346. doi:10.1016/j.susc.2006.01.162 CrossRefGoogle Scholar
  25. Maeda Y (1995) Visible photoluminescence from nanocrystallite Ge embedded in a glassy SiO2 matrix: evidence in support of the quantum-confinement mechanism. Phys Rev B 51:1658–1670. doi:10.1103/PhysRevB.51.1658 CrossRefGoogle Scholar
  26. Maeda Y, Tsukamoto N, Yazawa Y, Kanemitsu Y, Masumoto Y (1991) Visible photoluminescence of Ge microcrystals embedded in SiO2 glassy matrices. Appl Phys Lett 59:3168–3170. doi:10.1063/1.105773 CrossRefGoogle Scholar
  27. Mardare D, Luca D, Teodorescu CM, Macovei D (2007) On the hydrophilicity of nitrogen-doped TiO2 thin films. Surf Sci 601:4515–4520. doi:10.1016/j.susc.2007.04.156 CrossRefGoogle Scholar
  28. Morgan WE, Van Wazer JR (1973) Binding energy shifts in the x-ray photoelectron spectra of a series of related Group IVa compounds. J Phys Chem 77:964–969. doi:10.1021/j100626a023 CrossRefGoogle Scholar
  29. Nguyen TP, Lefrant S (1989) XPS study of SiO thin films and SiO–metal interfaces. J Phys Cond Matter 1:5197–5204. doi:10.1088/0953-8984/1/31/019 CrossRefGoogle Scholar
  30. Nogami M, Abe Y (1994) Sol–gel method for synthesizing visible photoluminescent nanosized Ge-crystal-doped silica glasses. Appl Phys Lett 65:2545–2547. doi:10.1063/1.112630 CrossRefGoogle Scholar
  31. Nogami M, Abe Y (1997) Sol–gel synthesis of Ge nanocrystals-doped glass and its photoluminescence. J Sol Gel Sci Tehnol 9:139–143. doi:10.1023/A:1026461029767 Google Scholar
  32. Nozaki S, Sato S, Rath S, Ono H, Morisaki H (1999) Optical properties of tetragonal germanium nanocrystals deposited by the cluster-beam evaporation technique: light emitting new material for future. Bull Mater Sci 22:377–381. doi:10.1007/BF02749945 CrossRefGoogle Scholar
  33. Park CJ, Cho KH, Yang W-C, Cho HY, Choi S-H, Elliman RG, Han JH, Kim C (2006) Large capacitance-voltage hysteresis loops in SiO2 films containing Ge nanocrystals produced by ion implantation and annealing. Appl Phys Lett 88(071916):1–3. doi:10.1063/1.2175495 Google Scholar
  34. Peibst R, Durkop T, Bugiel E, Fissel A, Costina I, Hofmann KR (2009) Driving mechanisms for the formation of nanocrystals by annealing of ultrathin Ge layers in SiO2. Phys Rev B 79(195316):1–13. doi:10.1103/PhysRevB.79.195316 Google Scholar
  35. Powder Diffraction File. http://www.icdd.com
  36. Rodríguez A, Morana B, Sangrador J, Rodríguez T, Kling A, Ortiz MI, Ballesteros C (2009) Formation of Ge nanocrystals and evolution of the oxide matrix in as-deposited and annealed LPCVD SiGeO films. Superlattices Microstruct 45:343–348. doi:10.1016/j.spmi.2008.10.037 CrossRefGoogle Scholar
  37. Shalvoy RB, Fisher GB, Stiles PJ (1977) Bond ionicity and structural stability of some average-valence-five materials studied by x-ray photoemission. Phys Rev B 15:1680–1697. doi:10.1103/PhysRevB.15.1680 CrossRefGoogle Scholar
  38. Shen JK, Wu XL, Yuan RK, Tang N, Zou JP, Mei YF, Tan C, Bao XM (2000) Enhanced ultraviolet photoluminescence from SiO2/Ge:SiO2/SiO2 sandwiched structure. Appl Phys Lett 77:3134–3136. doi:10.1063/1.1325399 CrossRefGoogle Scholar
  39. Stoica TF, Gartner M, Teodorescu VS, Stoica T (2007) Ge dots embedded in silicon dioxide using sol–gel deposition. J Optoelectron Adv Mater 9:3271–3274. http://inoe.inoe.ro/joam/index.php?option=magazine&op=view&idu=1004&catid=18 Google Scholar
  40. Takeoka S, Fujii M, Hayashi S, Yamamoto K (1998) Size-dependent near-infrared photoluminescence from Ge nanocrystals embedded in SiO2 matrices. Phys Rev B 58:7921–7925. doi:10.1103/PhysRevB.58.7921 CrossRefGoogle Scholar
  41. Teodorescu VS, Blanchin MG (2009) Fast and simple specimen preparation for TEM studies of oxide films deposited on silicon wafers. Microsc Microanal 15:15–19. doi:10.1017/S1431927609090011 CrossRefGoogle Scholar
  42. Teodorescu CM, Socol G, Negrila C, Luca D, Macovei D (2010) Nanostructured thin layers of vanadium oxides doped with cobalt, prepared by pulsed laser ablation: chemistry, local atomic structure, morphology and magnetism. J Exp Nanosci. doi:10.1080/17458081003671675.
  43. Wagner CD, Zatko DA, Raymond RH (1980) Use of the oxygen KLL Auger lines in identification of surface chemical states by electron spectroscopy for chemical analysis. Anal Chem 52:1445–1451. doi:10.1021/ac50059a017 CrossRefGoogle Scholar
  44. Wagner CD, Davis LE, Zeller MV, Taylor JA, Raymond RM, Gale LH (1981) Empirical atomic sensitivity factors for quantitative analysis by electron spectroscopy for chemical analysis. Surf Interface Anal 3:211–225. doi:10.1002/sia.740030506 CrossRefGoogle Scholar
  45. Walters RJ, Bourianoff GI, Atwater HA (2005) Field-effect electroluminescence in silicon nanocrystals. Nat Mater 4:143–146. doi:10.1038/nmat1307 CrossRefGoogle Scholar
  46. Wosylus A, Prots Y, Schnelle W, Hanfland M, Schwarz U (2008) Crystal structure refinements of Ge(tP12), physical properties and pressure-induced phase transformation Ge(tP12) ↔ Ge(tI4). Z Naturforsch B 63b:608–614. http://www.znaturforsch.com/ab/v63b/63b0608.pdf
  47. Yang HQ, Wang XJ, Shi HZ, Xie SH, Wang FJ, Gu XX, Yao X (2002) Photoluminescence of Ge nanodots embedded in SiO2 glasses fabricated by a sol–gel method. Appl Phys Lett 81:5144–5146. doi:10.1063/1.1506943 CrossRefGoogle Scholar
  48. Yang HQ, Yang RL, Wan XQ, Wan WL (2004) Structure and photoluminescence of Ge nanodots with different sizes embedded in SiO2 glasses fabricated by a sol–gel method. J Cryst Growth 261:549–556. doi:10.1016/j.jcrysgro.2003.08.081 CrossRefGoogle Scholar
  49. Yang HQ, Yao X, Xie SH, Wang XJ, Liu SX, Fang Y, Gu XX, Wang FJ (2005) Structure and photoluminescence of Ge nanodots embedded in SiO2 gel glasses fabricated at different temperatures. Opt Mater 27:725–730. doi:10.1016/j.optmat.2004.09.017 CrossRefGoogle Scholar
  50. Yang M, Chen TP, Ding L, Wong JI, Liu Y, Zhang WL, Zhang S, Zhu F, Goh WP (2009) Implant energy-dependent enhancement of electroluminescence from Ge-implanted SiO2 thin films. Electrochem Solid State Lett 12:H238–H240. doi:10.1149/1.3118524 CrossRefGoogle Scholar
  51. Zhang FX, Wang WK (1995) Crystal structure of germanium quenched from the melt under high pressure. Phys Rev B 52:3113–3116. doi:10.1103/PhysRevB.52.3113 CrossRefGoogle Scholar

Copyright information

© Springer Science+Business Media B.V. 2010

Authors and Affiliations

  • Ionel Stavarache
    • 1
  • Ana-Maria Lepadatu
    • 1
  • Nicoleta G. Gheorghe
    • 1
  • Ruxandra M. Costescu
    • 1
  • George E. Stan
    • 1
  • Dan Marcov
    • 1
  • Adrian Slav
    • 1
  • Gheorghe Iordache
    • 1
  • Tionica F. Stoica
    • 1
  • Vladimir Iancu
    • 2
  • Valentin S. Teodorescu
    • 1
  • Cristian M. Teodorescu
    • 1
  • Magdalena Lidia Ciurea
    • 1
  1. 1.National Institute of Materials PhysicsMagureleRomania
  2. 2.“Politehnica” University of BucharestBucharestRomania

Personalised recommendations