To obtain the heavily P-doped Si QD thin films, the P atoms diffusion process by post-annealing has been being developed since the P2O3 target is hard to be well made.
For the heavily P-doped Si QD thin films, the lowly P-doped GSRO-ML thin films are deposited by co-sputtering the lowly P-doped (~1×1018 cm-3) Si and pure SiO2 targets, and then, the as-deposited samples are annealed at 1100°C for the Si QDs
78
formation. After annealing, the POCl3 films are deposited on the Si QD thin films and annealed at 850°C by furnace for the P atoms diffusion. Finally, the residual POCl3
films are removed by a wet-etched process. So far, the PV properties of the P-doped Si QD thin films by diffusion process are obviously better than those of the lowly P-doped Si QD thin films. Hence, it represents the P atoms diffusion process is indeed a feasible method for the heavily P-doped Si QD thin films development.
A-3 Summary
The heavily B- and P-doped Si QD thin films have been developed, and the preliminary results reveal the feasible and great potential on PV properties. Next, more enhancements for the Si QD thin films on Si wafers will be studied. In the future works, the heavily B- and P-doped Si QD thin films will be integrated for the high efficiency all Si QD thin film SCs, and we deeply believe the third generation SCs can be achieved by the Si-based tandem SCs integrating the super-high density of Si QDs utilizing our proposed GSRO-ML structure.
79
References
[1] German Solar Industry Association, http://www.solarwirtschaft.de/en.html [2] EuPD Research, http://www.eupd-research.com/
[3] John Wiley & Sons, Inc, http://as.wiley.com/WileyCDA/Section/index.html [4] National Center for Photovoltaics (NCPV), National Renewable Energy
Laboratory (NREL), http://www.nrel.gov/ncpv/
[5] M. A. Green, “Third generation photovoltaics: ultra-high conversion efficiency at low cost, ” Prog. Photovolt: Res. Appl. 9, 123 (2001)
[6] Wikipedia, Sunlight, http://en.wikipedia.org/wiki/Sunlight
[7] C. S. Garoufalis and A. D. Zdetsis, “High level ab initio calculations of the optical gap of small silicon quantum dots,” Phys. Rev. Lett. 87, 276402 (2001) [8] S. Mirabella, R. Agosta, G. Franzò, I. Crupi, M. Miritello, R. L. Savio, M. A. D.
Stefano, S. D. Marco, F. Simone, and A. Terrasi, “Light absorption in silicon quantum dots embedded in silica,” J. Appl. Phys. 106, 103505 (2009)
[9] Z. Kang, Y. Liu, C. H. A. Tsang, D. D. D. Ma, X. Fan, N. B. Wong, and S. T.
Lee, “Water-soluble silicon quantum dots with wavelength-tunable photo- luminescence,” Adv. Mater. 21, 661 (2009)
[10] G. Conibeer, M. A. Green, R. Corkish, Y. Cho, E. C. Cho, C. W. Jiang, T.
Fangsuwannarak, E. Pink, Y. Huang, T. Puzzer, T. Trupke, B. Richards, A.
Shalav, and K. L. Lin, “Silicon nanostructures for third generation photovoltaic solar cells,” Thin Solid Films 511/512, 654 (2006)
[11] M. Zacharias, J. Heitmann, R. Scholz, U. Kahler, M. Schmidt, and J. Blasing,
“Size-controlled highly luminescent silicon nanocrystals: A SiO/SiO2
superlattice approach,” Appl. Phys. Lett. 80, 661 (2002)
80 photovoltaic cells,” Thin Solid Films 516, 6748 (2008)
[14] G. Scardera, T. Puzzer, D. McGrouther, E. Pink, T. Fangsuwannarak, G.
Conibeer, and M. A. Green, “Investigating large area fabrication of silicon quantum dots in a nitride matrix for photovoltaic applications,” IEEE Photovoltaic Energy Conversion 1, 122 (2006)
[15] D. Song, E. C. Cho, G. Conibeer, C. Flynn, Y. Huang, and M. A. Green,
“Structural, electrical and photovoltaic characterization of Si nanocrystals embedded SiC matrix and Si nanocrystals/c-Si heterojunction devices,” Sol.
Energy Mater. Sol. Cells 92, 474 (2008)
[16] E. C. Cho, S. Park, X. Hao, D. Song, G. Conibeer, S. C. Park, and M. A. Green,
“Silicon quantum dot/crystalline silicon solar cells,” Nanotechnology 19, 245201 (2008)
[17] C. Feser, J. Lacombe, K. V. Maydell, and C. Agert, “A simulation study towards a new concept for realization of thin film triple junction solar cells based on group IV elements,” Prog. Photovolt: Res. Appl. 20, 74 (2012)
[18] X. J. Hao, E. C.Cho, C. Flynn, Y. S. Shen, S. C. Park, G. Conibeer, and M. A.
Green, “Synthesis and characterization of boron-doped Si quantum dots for all-Si quantum dot tandem solar cells,” Sol. Energy Mater. Sol. Cells 93, 273 (2009)
81
“Doping- and size-dependent photovoltaic properties of p-type Si-quantum-dot heterojunction solar cells: correlation with photoluminescence,” Appl. Phys. Lett.
97, 072108 (2010)
[22] G. Conibeer, M. A. Green, D. Konig, I. Perez-Wurfl, S. Huang, X. Hao, D. Di, L.
Shi, S. Shrestha, B. Puthen-Veetil, Y. So, B. Zhang, and Z. Wan, “Silicon quantum dot based solar cells: addressing the issues of doping, voltage and current transport,” Prog. Photovolt: Res. Appl. 19, 813 (2010)
[23] H. Bartzsch, D. Glöß, P. Frach, M. Gittner, E. Schultheiß, W. Brode, and J.
Hartung, “Electrical insulation properties of sputter-deposited SiO2, Si3N4 and Al2O3 films at room temperature and 400°C,” Phys. Status Solidi A 206, 514 (2009)
[24] B. H. Lai, C. H. Cheng, and G. R. Lin, “Multicolor ITO/SiOx/p-Si/Al light emitting diodes with improved emission efficiency by small Si quantum dots,”
IEEE J. Quantum Electron. 47, 698 (2011)
[25] C. H. Cheng, Y. C. Lien, C. L. Wu, and G. R. Lin, “Mutlicolor electro- luminescent Si quantum dots embedded in SiOx thin film MOSLED with 2.4%
external quantum efficiency,” Opt. Express 21, 391 (2013)
82
[26] J. M. Shieh, W. C. Yu, J. Y. Huang, C. K. Wang, B. T. Dai, H. Y. Jhan, C. W. Hsu, H. C. Kuo, F. L. Yang, and C. L. Pan, “Near-infrared silicon quantum dots metal- oxide-semiconductor field-effect transistor photodetector,” Appl. Phys. Lett. 94, 241108 (2009)
[27] Y. C. Lien,J. M. Shieh, W. H. Huang, C. H. Tu, C. Wang, C. H. Shen, B. T. Dai, C. L. Pan, C. M. Hu, and F. L. Yang, “Fast programming metal-gate Si quantum dot nonvolatile memory using green nanosecond laser spike annealing,” Appl.
Phys. Lett. 100, 143501 (2012)
[28] C. W. Jiang, M. A. Green, E. C. Cho, and G. Conibeer, “Resonant tunneling through defects in an insulator: Modeling and solar cell applications,” J. Appl.
Phys. 96, 5006 (2004)
[29] M. A. Green, E. C. Cho, Y. Cho, Y. Huang, E. Pink, T. Trupke, A. Lin, T.
Fangsuwannarak, T. Puzzer, G. Conibeer, and R. Corkish, “All-silicon tandem cells based on “artificial” semiconductor synthesised using silicon quantum dots in a dielectric matrix,” Proceedings of the 20th European Photovoltaic Solar Energy Conference and Exhibition, pp. 3-6, Barcelona, Spain (2005)
[30] J. W. Luo, P. Stradins, and A. Zunger, “Matrix-embedded silicon quantum dots for photovoltaic applications: A theoretical study of critical factors,” Energy Environ. Sci. 4, 2546 (2011)
[31] C. F. Lin, W. T. Tseng, and M. S. Feng, “Formation and characteristics of silicon nanocrystals in plasma-enhanced chemical-vapor-deposited silicon-rich oxide,” J. Appl. Phys. 87, 2808 (2000)
[32] T. W. Kim, C. H. Cho, B. H. Kim, and S. J. Park, “Quantum confinement effect in crystalline silicon quantum dots in silicon nitride grown using SiH4 and NH3,”
Appl. Phys. Lett. 88, 123102 (2006)
[33] K. Y. Kuo, S. W. Hsu, P. R. Huang, W. L. Chuang, C. C. Liu, and P. T. Lee,
“Optical properties and sub-bandgap formation of nano-crystalline Si quantum dots embedded ZnO thin film,” Opt. Express 20, 10470 (2012)
83
[34] Ü . Ö zgür, Y. I. Alivov, C. Liu, A. Teke, M. A. Reshnikov, S. Dogan, V. Avrutin, S.
J. Cho, and H. Morkoç, “A comprehensive review of ZnO materials and devices,”
J. Appl. Phys. 98, 041301 (2005)
[35] Wikipedia, RCA, http://en.wikipedia.org/wiki/RCA_clean
[36] Colorado School of Mines, http://inside.mines.edu/fs_home/cwolden/chen435/
clean.htm
[37] Wikipedia, Ultrasonic Cleaning, http://en.wikipedia.org/wiki/Ultrasonic_
cleaning
[38] Wikipedia, Reactive Ion Etching, http://en.wikipedia.org/wiki/Reactive-ion_
etching
[39] Wikimedia Commons, Thermal Evaporation, https://commons.wikimedia.org/
wiki/File:Fig.6_(a)_Vapor_thermal_Evaporation_.JPG
[40] The Prashant Kamat Laboratory, University of Notre Dame, http://www3.nd.edu/
~kamat lab/facilities_spectroscopy.html
[41] A. Rastelli, S. Kiravittaya, L. Wang, C. Bauer, and O.G. Schmidt, “Micro-photo- luminescence spectroscopy of hierarchically self-assembled quantum dots,”
Physica E 32, 29 (2006)
[42] M. F. Toney, T. C. Huang, S. Brennan, and Z. Rek, “X-ray depth profiling of iron oxide thin film,” J. Mater. Res. 3, 351 (1988)
[43] Arizona State University, http://www.public.asu.edu/~laserweb/woodbury /classes/chm467/bioanalytical/spectroscopy/absflr.html
[44] Wikipedia, Atomic Force Microscopy, http://en.wikipedia.org/wiki/Atomic_
force_microscopy
[45] Wikipedia, Transmission Electron Microscopy, http://en.wikipedia.org/wiki/
Transmission_electron_microscopy
84
[46] C. F. Lin, M. Zhang, S. W. Liu, T. L. Chiu, and J. H. Lee, “High photoelectric conversion efficiency of metal phthalocyanine/fullerene heterojunction photovoltaic device,” Int. J. Mol. Sci. 12, 505 (2011)
[47] Q. Cheng, E. Tam, S. Xu, and K. Ostrikov, “Si quantum dots embedded in an amorphous SiC matrix: nanophase control by non-equilibrium plasma hydrogenation,” Nanoscale 2, 594 (2010)
[48] G. Viera, S. Huet, and L. Boufendi “Crystal size and temperature measurements in nanostructured silicon using Raman spectroscopy,” J. Appl. Phys. 90, 4175 (2001)
[49] K. S. Min, K. V. Shcheglov, C. M. Yang, H. A. Atwater, M. L. Brongersma, and A. Polman, “Defect-related versus excitonic visible light emission from ion beam synthesized Si nanocrystals in SiO2,” Appl. Phys. Lett. 69, 2033 (1996) [50] X. Wen, L. V. Dao, P. Hannaford, E. C. Cho, Y. H. Cho, and M. A. Green,
“Excitation dependence of photoluminescence in silicon quantum dots,” New J.
Phys. 9, 337 (2007)
[51] X. Wen, L. V. Dao, and P. Hannaford, “Temperature dependence of photo- luminescence in silicon quantum dots,” J. Phys. D: Appl. Phys. 40, 3573 (2007) [52] M. A. Green, E. C. Cho, Y. Cho, Y. Huang, E. Pink, T. Trupke, A. Lin, T.
Fangsuwannarak, T. Puzzer, G. Conibeer, and R. Corkish, “All-silicon tandem cells based on “artificial” semiconductor synthesised using silicon quantumdots in a dielectric matrix,” Proceedings of the 20th European Photovoltaic Solar Energy Conference and Exhibition, pp. 3-6, Barcelona, Spain (2005)
[53] C. Meier, A. Gondorf, S. Lüttjohann, A. Lorke, and H. Wiggers, “Silicon nano- particles: absorption, emission, and the nature of the electronic bandgap,” J.
Appl. Phys. 101, 103112 (2007)
85
[54] N. Yoshida, Y. Shimizu, T. Honda, T. Yokoi, and S. Nonomura, “A study of absorption coefficient spectra in a-Si:H films near the transition from amorphous to crystalline phase measured by resonant photothermal bending spectroscopy,”
J. Non-Cryst. Solids 354, 2164 (2008)
[55] V. Osinniy, S. Lysgaard, V. Kolkovsky, V. Pankratov, and A. N. Larsen,
“Vertical charge-carrier transport in Si nanocrystal/SiO2 multilayer structures,”
Nanotechnology 20, 195201 (2009)
[56] S. Park, E. Cho, D. Song, G. Conibeer, and M. A. Green, “n-Type silicon quantum dots and p-type crystalline silicon heteroface solar cells,” Sol. Energy Mater. Sol. Cells 93, 684 (2009)
[57] H. Wong and H. Iwai, “On the scaling issues and high-k replacement of ultrathin gate dielectrics for nanoscale MOS transistors,” Microelectron. Eng. 83, 1867 (2006)
[58] H. W. Lau, O. K. Tan, and D. A. Trigg, “Charge injection and tunneling mechanism of solid state reaction silicon nanocrystal film,” Appl. Phys. Lett. 89, 113119 (2006)
[59] I. Perez-Wurfl, X. Hao, A. Gentle, D. H. Kim, G. Conibeer, and M. A. Green,
“Si nanocrystal p-i-n diodes fabricated on quartz substrates for third generation solar cell applications,” Appl. Phys. Lett. 95, 153506 (2009)
[60] G. Faraci, S. Gibilisco, P. Russo, A. R. Pennisi, G. Compagnini, S. Battiato, R.
Puglisi, and S. L. Rosa, “Si/SiO2 core shell clusters probed by Raman spectroscopy,” Eur. Phys. J. B 46, 457 (2005)
[61] K. A. Alim, V. A. Fonoberov, and A. A. Balandin, “Origin of the optical phonon frequency shifts in ZnO quantum dots,” Appl. Phys. Lett. 86,053103 (2005) [62] Q. J. Cheng, S. Xu, and K. Ostrikov, “Structural evolution of nanocrystalline
silicon thin films synthesized in high-density, low-temperature reactive plasmas,”
Nanotechnology 20, 215606 (2009)
86
[63] M. Zacharias, J. Blasing, P. Veit, L. Tsybeskov, K. Hirschman, and P. M. Fauchet,
“Thermal crystallization of amorphous Si/SiO2 superlattices,” Appl. Phys. Lett.
74, 2614 (1999)
[64] E. C. Cho, M. A. Green, G. Conibeer, D. Song, Y. H. Cho, G. Scardera, S.
Huang, S. Park, X. J. Hao, Y. Huang, and L. V. Dao, “Silicon quantum dots in a dielectric matrix for all-silicon tandem solar cells,” Adv. OptoElectron. 2007, 69578 (2007)
[65] J. B. You, X. W. Zhang, Y. M. Fan, Z. G. Yin, P. F. Cai, and N. F. Chen, “Effect of deposition conditions on optical and electrical properties of ZnO films prepared by pulsed laser deposition,” Appl. Surf. Sci. 197-198, 363 (2002)
[66] D. H. Kim, H. Jeon, G. Kim, S. Hwangboe, V. P. Verma, W. Choi, and M. Jeon,
“Comparison of the optical properties of undoped and Ga-doped ZnO thin films deposited using RF magnetron sputtering at room temperature,” Opt. Commun.
281, 2120 (2008)
[67] J. M. Shieh, W. C. Yu, J. Y. Huang, C. K. Wang, B. T. Dai, H. Y. Jhan, C. W. Hsu, H. C. Kuo, F. L. Yang, and C. L. Pan, “Near-infrared silicon quantum dots metal-oxide-semiconductor field-effect transistor photodetector,” Appl. Phys.
Lett. 94, 241108 (2009)
[68] Y. G. Wang, S. P. Lau, H. W. Lee, S. F. Yu, B. K. Tay, X. H. Zhang, and H. H.
Hng, “Photoluminescence study of ZnO films prepared by thermal oxidation of Zn metallic films in air,” J. Appl. Phys. 94, 354 (2003)
[69] S. Fujihara, Y. Ogawa, and A. Kasai, “Tunable visible photoluminescence from ZnO thin films through Mg-doping and annealing,” Chem. Mater. 16, 2965 (2004)
[70] X. X. Wang, J. G. Zhang, L. Ding, B. W. Cheng, W. K. Ge, J. Z. Yu, and Q. M.
Wang, “Origin and evolution of photoluminescence from Si nanocrystals embedded in a SiO2 matrix,” Phys. Rev. B 72, 195313 (2005)
87
[71] Y. C. Liu, S. K. Tung, and J. H. Hsieh, “Influence of annealing on optical properties and surface structure of ZnO thin films,” J. Cryst. Growth 287, 105 (2006)
[72] Y. P. Chan, J. H. Lin, C. C. Hsu, and W. F. Hsieh, “Near-resonant high order nonlinear absorption of ZnO thin films,” Opt. Express 16, 19900 (2008)
[73] Z. Ma, X. Liao, G. Kong, and J. Chu, “Absorption spectra of nanocrystalline silicon embedded in SiO2 matrix,” Appl. Phys. Lett. 75, 1857 (1999)
[74] L. W. Lai and C. T. Lee, “Investigation of optical and electrical properties of ZnO thin films,” Mater. Chem. Phys. 110, 393 (2008)
[75] K. B. Sundaram and A. Khan, “Characterization and optimization of zinc oxide films by r.f. magnetron sputtering,” Thin Solid Films 295, 87 (1997)
[76] D. Di, H. Xu, I. Perez-Wurfl, M. A. Green, and G. Conibeer, “Improved nanocrystal formation, quantum confinement and carrier transport properties of doped Si quantum dot superlattices for third generation photovoltaics,” Prog.
Photovolt.: Res. Appl. doi: 10.1002/pip.1230 (2011)
[77] J. D. Lee, C. Y. Park, H. S. Kim, J. J. Lee, and Y. G. Choo, “A study of conduction of ZnO film/p-Si heterojunction fabricated by photoinduced electrodeposition under illumination” J. Phys. D: Appl. Phys. 43, 365403 (2010) [78] S. Mridha and D. Basak, “Ultraviolet and visible photoresponse properties of
n-ZnO/p-Si heterojunction,” J. Appl. Phys. 101, 083102 (2007)
[79] N. Zebbar, Y. Kheireddine, K. Mokeddem, A. Hafdallah, M. Kechouane, and M.
S. Aida, “Structural, optical and electrical properties of n-ZnO/p-Si heterojunction prepared by ultrasonic spray,” Mater. Sci. Semicond. Process 14, 229 (2011)
[80] Y. Zhang, J. Xu, B. Lin, Z. Fu, S. Zhong, C. Liu, and Z. Zhang, “Fabrication and electrical characterization of nanocrystalline [ZnO/Si] heterojunctions,” Appl.
Surf. Sci. 252, 3449 (2006)
88
[81] Dhananjay, J. Nagaraju, and S. B. Krupanidhi, “Investigations on zinc oxide thin films grown on Si (100) by thermal oxidation,” Mater. Sci. Eng. B 137, 126 (2007)
[82] B. P. Veettil, “Modelling and characterization of carrier transport through nanostructures,” PhD thesis, University of New South Wales, School of Photovoltaic and Renewable Energy Engineering (2012)
[83] T. Fangsuwannarak, “Electronic and optical characterisations of silicon quantum dots and its applications in solar cells,” PhD thesis, University of New South Wales, Centre of Excellence for Advanced Silicon Photovoltaics and Photonics (2007)
89