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Experiments towards size and dopant control of germanium quantum dots for solar applications

1 Department of Chemistry, Rice University, Houston, Texas 77005, USA
2 Department of Mechanical Engineering and Materials Science, Rice University, Houston, Texas 77005, USA
3 Energy Safety Research Institute (ESRI), Swansea University Bay Campus, Swansea, SA1 8EN, Wales, UK

Topical Section: The solar cell

While the literature for the doping of silicon quantum dots (QDs) and nanocrystals (NCs) is extensive, reports of doping their germanium analogs are sparse. We report a range of attempts to dope Ge QDs both during and post-synthesis. The QDs have been characterized by TEM, XPS, and I/V measurements of SiO2 coated QD thin films in test cells using doped Si substrates. The solution synthesis of Ge QDs by the reduction of GeCl4 with LiAlH4 results in Ge QDs with a low level of chlorine atoms on the surface; however, during the H2PtCl6 catalyzed alkylation of the surface with allylamine, to enable water solubility of the Ge QDs, chlorine functionalization of the surface occurs resulting in p-type doping of the QD. A similar location of the dopant is proposed for phosphorus when incorporated by the addition of PCl3 during QD synthesis; however, the electronic doping effect is greater. The detected dopants are all present on the surface of the QD (s-type), suggesting a self-purification process is operative. Attempts to incorporate boron or gallium during synthesis were unsuccessful.
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1.Soga T (2006) Nanostructured Materials for Solar Energy Conversion, New York: Elsevier.

2.Littau KA, Szajowski PJ, Muller AJ, et al. (1993) A luminescent silicon nanocrystal colloid via a high-temperature aerosol reaction. J Phys Chem 97: 1224–1230.    

3.Ni Z, Pi X, Yang D (2014) Doping Si nanocrystals embedded in SiO2 with P in the framework of density functional theory. Phys Rev B 89: 035312.    

4.Zhou S, Pi X, Ni Z, et al. (2015) Boron- and phosphorus-hyperdoped silicon nanocrystals. Part Part Syst Charact 32: 213–221.    

5.Cullis AG, Canham LT, Calcott PDJ (1997) The structural and luminescent properties of porous silicon. J Appl Phys 82: 909–965.    

6.Oliva-Chatelain BL, Ticich TM, Barron AR (2015) Doping silicon nanocrystals and quantum dots. Nanoscale [in press].

7.Sugimoto H, Fujii M, Imakita K, et al. (2012) All-inorganic near-infrared luminescent colloidal silicon nanocrystals: high dispersibility in polar liquid by phosphorus and boron codoping. J Phys Chem C 116: 17969−17974.

8.Ni Z, Pi X, Ali M, et al. (2015) Freestanding doped silicon nanocrystals synthesized by plasma. J Phys D: Appl Phys 48: 314006.    

9.Ruddy DA, Erslev PT, Habas SE, et al. (2013) Surface chemistry exchange of alloyed germanium nanocrystals: a pathway toward conductive group IV nanocrystal films. J Phys Chem Lett 4: 416–421.    

10.Baldwin RK, Zou J, Pettigrew KA, et al. (2006) The preparation of a phosphorus doped silicon film from phosphorus containing silicon nanoparticles. Chem Commun 6: 658–660.

11.Wheeler LM, Neale NR, Chen T, et al. (2013) Hypervalent surface interactions for colloidal stability and doping of silicon nanocrystals. Nat Commun 4: 2197.

12.Prabakar S, Shiohara A, Hanada K, et al. (2010) Size controlled synthesis of germanium quantum nanocrystals by hydride reducing agents and their biological applications. Chem Mater 22: 482–486.    

13.Oliva BL, Barron AR (2012) Thin films of silica imbedded silicon and germanium quantum dots by solution processing. Mater Sci Semicond Proc 15: 713–721.    

14.Ashby SP, Chao Y (2014) Use of electrochemical etching to produce doped phenylacetylene functionalized particles and their thermal stability. J Electron Mater 43: 2006–2010.    

15.Garrone E, Geobaldo F, Rivolo P, et al. (2005) A nanostructured porous silicon near insulator becomes either a p- or an n-type semiconductor upon gas adsorption. Adv Mater 17: 528–531.    

16.Zhang L, Zhang J, Schmandt N, et al. (2005) AFM and STM characterization of thiol and thiophene functionalized SWNTs: pitfalls in the use of gold nanoparticles to determine the extent of side-wall functionalization in SWNTs. Chem Commun 2005: 5429–5430.

17.Zhang L, Yang J, Edwards CL, et al. (2005) Diels alder addition to fluorinated single walled carbon nanotubes. Chem Commun 2005: 3265–3267.

18.Zeng L, Zhang L, Barron AR (2005) Tailoring aqueous solubility of functionalized single-wall carbon nanotubes over a wide pH range through substituent chain length. Nano Lett 5: 2001–2004.    

19.Rutledge H, Oliva-Chatelain BL, Maquire-Boyle SJ, et al. (2014) Imbedding germanium quantum dots in silica by a modified Stober method. Mater Sci Semicond Proc 17: 7–12.

20.Yang J, Barbarich TJ, Barron AR (2013) SiO2 template-derived polyurethane and alumina nanoparticle-polyurethane lithium ion separator membranes. Main Group Chem 12: 45–56.

21.Lu Y-T, Barron AR (2015) In-situ fabrication of a self-aligned selective emitter silicon solar cell using the gold top contacts to facilitate the synthesis of a nanostructured black silicon anti-reflective layer instead of an external metal nanoparticle catalyst. ACS Appl Mater Interfaces 7: 11802–11814.    

22.Grossi V, Ottaviano L, Santucci S, et al. (2010) XPS and SEM studies of oxide reduction of germanium nanowires. J Non-Cryst Sol 356: 1988–1993.    

23.Lu ZH (1996) Air-stable Cl-terminated Ge (111). Appl Phys Lett 68: 520–522.    

24.Kim S, Walker B, Park SY, et al. (2014) Size tailoring of aqueous germanium nanoparticle dispersions. Nanoscale 6: 10156–10160.    

25.Ma Y, Chen X, Pi X, et al. (2011) Theoretical study of chlorine for silicon nanocrystals. J Phys Chem C 115: 12822–12825.

26.Straumanis ME, Aka EZ (1952) Lattice parameters, coefficients of thermal expansion, and atomic weights of purest silicon and germanium. J Appl Phys 23: 330–334.    

27.Sze SM (1985) Semiconductor Devices: Physics and Technology, New York: Wiley.

28.Vollhardt KPC, Schore NE (2003) Organic Chemistry: Structure and Function, New York: W. H. Freeman and Company.

29.Livingston JD (1999) Electronic Properties of Engineering Materials, New York: John Wiley.

30.Yamauchi T, Tabuchi M, Nakamura A (2004) Size dependence of the work function in InAs quantum dots on GaAs (001) as studied by Kelvin force probe microscopy. Appl Phys Lett 84: 3834–3836.    

31.Alfaro P, Miranda A, Ramos AE, et al. (2006) Hydrogenated Ge nanocrystals: bandgap evolution with increasing size. Braz J Phys 36: 375–378.

32.Crouse C, Barron AR (2008) Reagent control over the size, uniformity, and composition of Co-Fe-Onanoparticles. J Mater Chem 18: 4146–4153.    

33.Baldwin RK, Pettigrew KA, Garno JC, et al. (2002) Room temperature solution synthesis of alkyl-capped tetrahedral shaped silicon nanocrystals. J Am Chem Soc 124: 1150–1151.    

34.Pearson GL, Bardeen, J (1949) Electrical properties of pure silicon and silicon alloys containing boron and phosphorus. Phys Rev 75: 865–883.    

35.Baldwin RK, Zhou J, Pettigrew KA, et al. (2006) The preparation of a phosphorus doped silicon film from phosphorus containing silicon nanoparticles. Chem Comm 2006: 658–660.

36.Binions R, Carmalt CJ, Parkin IP (2003) Germanium phosphide coatings from the atmospheric pressure chemical vapor deposition of GeX4 (X=Cl or Br) and PCychexH2. Polyhedron 22: 1683–1688.    

37.Ren J, Eckert H (2012) Quantification of short and medium range order in mixed network former glasses of the system GeO2-NaPO3: a combined NMR and X-ray photoelectron spectroscopy study. J Phys Chem C 116: 12747–12763.    

38.Konig D, Gutsch S, Gnaser H, et al. (2015) Location and electronic nature of phosphorus in the Si nanocrystal – SiO2 system. Sci Rep 5: 09702.    

39.Manna S, Prtljaga N, Das S, et al. (2012) Photophysics of resonantly and non-resonantly excited erbium doped Ge nanowires. Nanotechnology 23: 065702.    

40.Ebraheem S, El-Saied A (2013) Band gap determination from diffuse reflectance measurements of irradiated lead borate glass system doped with TiO2 by using diffuse reflectance technique. Mater Sci App 4: 324–329.

41.Ghobadi N (2013) Band gap determination using absorption spectrum fitting procedure. Intl Nano Lett 3: 1–4.

42.Norris DJ, Efros AL, Erwin SC (2008) Doped nanocrystals. Science 319: 1776–1779.


Copyright Info: © 2016, Andrew R. Barron, et al., licensee AIMS Press. This is an open access article distributed under the terms of the Creative Commons Attribution Licese (http://creativecommons.org/licenses/by/4.0)

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