SEMICONDUCTOR MATERIALS

Optimization of SnS active layer thickness for solar cell application

Yashika Gupta1, 2 and P. Arun1,

+ Author Affiliations

 Corresponding author: P. Arun, Email: arunp92@sgtbkhalsa.du.ac.in

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Abstract: This work presents a comparative study of n-SnS and p-SnS active layers for increased solar cell efficiency. Tin sulphide thin films of various thicknesses having p-type and n-type conductivity were fabricated by thermal evaporation. Both type of films had the same (113) orientation of the crystal planes with a constant tensile strain of ~ 0.003 and ~ 0.011, respectively. The persistent photocurrent was observed in all n-SnS and p-SnS samples with the current’s time decay constant decreasing with increasing film thickness. Hole mobility of thicker p-SnS films was found to be greater than the electron mobility in n-SnS samples, with mobility (both hole and electron) showing an increasing trend with film thickness. The optimum absorber layer thickness for both p- and n-SnS layers should have a high value of diffusion length for a given absorption coefficient and band-gap.

Key words: thin filmchalcogenidesoptical properties



[1]
Dong Q, Fang Y, Shao Y, et al. Electron-hole diffusion lengths > 175 μm in solution-grown CH3NH3PbI3 single crystals. Science, 2015, 347: 6225
[2]
Gao C, Shen H, Sun L. Preparation and properties of zinc blende and orthorhombic SnS films by chemical bath deposition. Appl Surf Sci, 2011, 257: 6750 doi: 10.1016/j.apsusc.2011.02.116
[3]
Sohila S, Rajalakshmi M, Ghosh C, et al. Optical and Raman Scattering studies on SnS nano-particles. J Alloys Compd, 2011, 509: 5843 doi: 10.1016/j.jallcom.2011.02.141
[4]
Fadavieslam M R, Shahtahmasebi N, Razaee-Roknabadi M, et al. A study of the photoconductivity and thermoelectric properties of SnxSy optical semiconductor thin films deposited by the spray pyrolysis technique. Phys Scr, 2011, 84: 035705 doi: 10.1088/0031-8949/84/03/035705
[5]
Gomez A, Martinez H, Calixto-Rodriguez M, et al. A study of the structural, optical and electrical properties of SnS thin films modified by plasma. J Mater Sci Eng B, 2013, 3: 352
[6]
Ogah O E, Reddy K R, Zoppi G, et al. Annealing studies and electrical properties of SnS-based solar cells. Thin Solid Films, 2011, 519: 7425 doi: 10.1016/j.tsf.2010.12.235
[7]
Leach M, Reddy K T R, Reddy M V, et al. Tin sulphide thin films synthesised using a two step process. Energy Procedia, 2012, 15: 371 doi: 10.1016/j.egypro.2012.02.045
[8]
Ristov M, Sinadinovski G, Grozdanov J, et al. Chemical deposition of tin(II) sulphide thin films. Thin Solid Films, 1989, 173: 53 doi: 10.1016/0040-6090(89)90536-1
[9]
Sajeesh T H, Jinesh K B, Rao M, et al. Unveiling the defect levels in SnS thin films for photovoltaic applications using photoluminescence technique. Phys Status Solidi A, 2010, 207: 1934 doi: 10.1002/pssa.200925593
[10]
Sinsermsuksakul P, Heo J, Noh W, et al. Atomic layer deposition of tin monosulfide thin films. Adv Energy Mater, 2011, 7: 1116
[11]
Sinsermsuksakul P, Hartman K, Kim S B, et al. Enhancing the efficiency of SnS solar cells via band-offset engineering with a zinc oxysulfide buffer layer. Appl Phys Lett, 2013, 102: 053901 doi: 10.1063/1.4789855
[12]
Stavrinadis A, Smith J M, Cattley C A, et al. SnS/PbS nanocrystal hetrojunction photovoltaics. Nanotechnology, 2010, 21: 185202 doi: 10.1088/0957-4484/21/18/185202
[13]
Jain P, Arun P. Photovoltaic performance of hybrid ITO/PEDOT:PSS/n-SnS/Al solar cell structure. J Semicond, 2016, 37: 074002 doi: 10.1088/1674-4926/37/7/074002
[14]
Jain P, Shokeen P, Arun P. Improved efficiency of plasmonic tin sulfide solar cells. J Mater Sci: Mater Elec, 2016, 27: 5107 doi: 10.1007/s10854-016-4401-0
[15]
Gupta Y, Arun P. Suitability of SnS thin films for photovoltaic application due to the existence of persistent photocurrent. Phys Status Solidi B, 2016, 253: 509 doi: 10.1002/pssb.v253.3
[16]
Vidal J, Lany S, d’Avezac M, et al. Band-structure, optical properties, and defect physics of the photovoltaic semiconductor SnS. Appl Phys Lett, 2012, 100: 032104 doi: 10.1063/1.3675880
[17]
Ninan G G, Kartha C S, Vijayakumar K P et al. Spray pyrolysed SnS thin films in n and p type: optimization of deposition process and characterization of samples. J Analyt Appl Pyrolysis, 2016, 120: 121 doi: 10.1016/j.jaap.2016.04.016
[18]
Ran F Y, Xiao Z, Toda Y, et al. n-type conversion of SnS by isovalent ion substitution: geometrical doping as a new doping route. Sci Rep, 2015, 5: 10428 doi: 10.1038/srep10428
[19]
Chandrashekhar H R, Humphreys R G, Zwick U, et al. Infrared and Raman spectra of the IV–VI compounds SnS and SnSe. Phys Rev B, 1977, 15: 2177 doi: 10.1103/PhysRevB.15.2177
[20]
Alim K A, Fonoberrov V A, Baladdin A A. Origin of the optical phonon frequency shifts in ZnO quantum dots. Appl Phys Lett, 20015, 86: 053103
[21]
Zhu J S, Lu X M, Jiang W, et al. Optical study on the size effects in BaTiO3 thin films. J Appl Phys, 1997, 81: 1392 doi: 10.1063/1.363875
[22]
Rajalakshmi M, Arora A K, Bendre B S, et al. Optical phonon confinement in zinc oxide nanoparticles. J Appl Phys, 2000, 87: 2445 doi: 10.1063/1.372199
[23]
Lucovsky G, Mikkelsen J C, Liang W Y, et al. Optical phonon anisotropies in the layer crystals SnS2 and SnSe2. Phys Rev B, 1976, 14: 1663 doi: 10.1103/PhysRevB.14.1663
[24]
Dang X Z, Wang C D, Yu E T, et al. Persistent photoconductivity and defect levels in n-type AlGaN/GaN hetrostructures. Appl Phys Lett, 1998, 72: 2745 doi: 10.1063/1.121077
[25]
Gupta Y, Arun P. Influence of Urbach tail on the refractive index of p-SnS thin films. Phys Status Solidi C, 2017, 14: 1600207
[26]
Tauc J. Absorption edge and internal electric fields in amorphous semiconductors. Mater Res Bull, 1970, 5: 721 doi: 10.1016/0025-5408(70)90112-1
[27]
Brus L E. Electron–electron and electron–hole interactions in small semiconductor crystallites: the size dependence of the lowest excited electronic state. J Chem Phys, 1984, 80: 4403 doi: 10.1063/1.447218
[28]
Sze S M. Physics of semiconductor devices. 2nd ed. John Wiley and Sons, Inc. 1981
[29]
Ran F Y, Xiao Z, Toda Y, et al. n-type conversion of SnS by isovalent ion substitution: Geometrical doping as a new doping route. Sci Rep, 2015, 5: 10428 doi: 10.1038/srep10428
[30]
Gupta Y, Arun P. Influence of strain on the sensitivity of tin sulphide films. Mater Chem Phys, 2017, 191: 86 doi: 10.1016/j.matchemphys.2017.01.029
Fig. 1.  (Color online) X-ray diffractograms of n-type and p-type films along with powder pattern showing similar crystal structure.

Fig. 2.  (Color online) The grain size of p-type and n-type films varying linearly with film thickness.

Fig. 3.  The SEM micrographs of n-SnS films with thicknesses (a) 480, (b) 600, and (c) 900 nm. This is compared to p-SnS films with thicknesses (d) 650, (e) 870, and (f) 960 nm.

Fig. 4.  (Color online) Raman spectra of n-and p-SnS films of thicknesses indicated.

Fig. 5.  (Color online) Variation of photocurrent with time for n-type SnS films of various thicknesses.

Fig. 6.  (Color online) The decay time constant fall with increasing film thickness for both n-SnS and p-SnS. The error in τ values is represented by the diameter of the circles enclosing the data points.

Fig. 7.  (Color online) The absorption spectra for (a) n-SnS and (b) p-SnS thin films of various samples have been compared. Spectrum have been slightly displaced with increasing film thickness for better viewing. (c) shows the variation of absorption coefficient (α) for p-SnS and n-SnS samples for various thicknesses, measured at 580 nm (yellow) wavelength. The error in α values is represented by the diameter of the circles enclosing the data points.

Fig. 8.  (Color online) The Tauc plots or (αhν)2 versus plots were used to determine the bandgap of SnS films of various thicknesses.

Fig. 9.  (Color online) Variation of the band-gap with increasing film thickness for both n-SnS and p-SnS.

Fig. 10.  (Color online) Variation of the μ, the majority charge carrier mobility with increasing film thickness for both n-SnS and p-SnS. The error in mobility values is represented by the diameter of the circles enclosing the data points.

Fig. 11.  (Color online) Variation of the diffusion length (LD) with increasing film thickness for both n-SnS and p-SnS. Curves were generated using the trendlines of Figs. 6 and 10.

[1]
Dong Q, Fang Y, Shao Y, et al. Electron-hole diffusion lengths > 175 μm in solution-grown CH3NH3PbI3 single crystals. Science, 2015, 347: 6225
[2]
Gao C, Shen H, Sun L. Preparation and properties of zinc blende and orthorhombic SnS films by chemical bath deposition. Appl Surf Sci, 2011, 257: 6750 doi: 10.1016/j.apsusc.2011.02.116
[3]
Sohila S, Rajalakshmi M, Ghosh C, et al. Optical and Raman Scattering studies on SnS nano-particles. J Alloys Compd, 2011, 509: 5843 doi: 10.1016/j.jallcom.2011.02.141
[4]
Fadavieslam M R, Shahtahmasebi N, Razaee-Roknabadi M, et al. A study of the photoconductivity and thermoelectric properties of SnxSy optical semiconductor thin films deposited by the spray pyrolysis technique. Phys Scr, 2011, 84: 035705 doi: 10.1088/0031-8949/84/03/035705
[5]
Gomez A, Martinez H, Calixto-Rodriguez M, et al. A study of the structural, optical and electrical properties of SnS thin films modified by plasma. J Mater Sci Eng B, 2013, 3: 352
[6]
Ogah O E, Reddy K R, Zoppi G, et al. Annealing studies and electrical properties of SnS-based solar cells. Thin Solid Films, 2011, 519: 7425 doi: 10.1016/j.tsf.2010.12.235
[7]
Leach M, Reddy K T R, Reddy M V, et al. Tin sulphide thin films synthesised using a two step process. Energy Procedia, 2012, 15: 371 doi: 10.1016/j.egypro.2012.02.045
[8]
Ristov M, Sinadinovski G, Grozdanov J, et al. Chemical deposition of tin(II) sulphide thin films. Thin Solid Films, 1989, 173: 53 doi: 10.1016/0040-6090(89)90536-1
[9]
Sajeesh T H, Jinesh K B, Rao M, et al. Unveiling the defect levels in SnS thin films for photovoltaic applications using photoluminescence technique. Phys Status Solidi A, 2010, 207: 1934 doi: 10.1002/pssa.200925593
[10]
Sinsermsuksakul P, Heo J, Noh W, et al. Atomic layer deposition of tin monosulfide thin films. Adv Energy Mater, 2011, 7: 1116
[11]
Sinsermsuksakul P, Hartman K, Kim S B, et al. Enhancing the efficiency of SnS solar cells via band-offset engineering with a zinc oxysulfide buffer layer. Appl Phys Lett, 2013, 102: 053901 doi: 10.1063/1.4789855
[12]
Stavrinadis A, Smith J M, Cattley C A, et al. SnS/PbS nanocrystal hetrojunction photovoltaics. Nanotechnology, 2010, 21: 185202 doi: 10.1088/0957-4484/21/18/185202
[13]
Jain P, Arun P. Photovoltaic performance of hybrid ITO/PEDOT:PSS/n-SnS/Al solar cell structure. J Semicond, 2016, 37: 074002 doi: 10.1088/1674-4926/37/7/074002
[14]
Jain P, Shokeen P, Arun P. Improved efficiency of plasmonic tin sulfide solar cells. J Mater Sci: Mater Elec, 2016, 27: 5107 doi: 10.1007/s10854-016-4401-0
[15]
Gupta Y, Arun P. Suitability of SnS thin films for photovoltaic application due to the existence of persistent photocurrent. Phys Status Solidi B, 2016, 253: 509 doi: 10.1002/pssb.v253.3
[16]
Vidal J, Lany S, d’Avezac M, et al. Band-structure, optical properties, and defect physics of the photovoltaic semiconductor SnS. Appl Phys Lett, 2012, 100: 032104 doi: 10.1063/1.3675880
[17]
Ninan G G, Kartha C S, Vijayakumar K P et al. Spray pyrolysed SnS thin films in n and p type: optimization of deposition process and characterization of samples. J Analyt Appl Pyrolysis, 2016, 120: 121 doi: 10.1016/j.jaap.2016.04.016
[18]
Ran F Y, Xiao Z, Toda Y, et al. n-type conversion of SnS by isovalent ion substitution: geometrical doping as a new doping route. Sci Rep, 2015, 5: 10428 doi: 10.1038/srep10428
[19]
Chandrashekhar H R, Humphreys R G, Zwick U, et al. Infrared and Raman spectra of the IV–VI compounds SnS and SnSe. Phys Rev B, 1977, 15: 2177 doi: 10.1103/PhysRevB.15.2177
[20]
Alim K A, Fonoberrov V A, Baladdin A A. Origin of the optical phonon frequency shifts in ZnO quantum dots. Appl Phys Lett, 20015, 86: 053103
[21]
Zhu J S, Lu X M, Jiang W, et al. Optical study on the size effects in BaTiO3 thin films. J Appl Phys, 1997, 81: 1392 doi: 10.1063/1.363875
[22]
Rajalakshmi M, Arora A K, Bendre B S, et al. Optical phonon confinement in zinc oxide nanoparticles. J Appl Phys, 2000, 87: 2445 doi: 10.1063/1.372199
[23]
Lucovsky G, Mikkelsen J C, Liang W Y, et al. Optical phonon anisotropies in the layer crystals SnS2 and SnSe2. Phys Rev B, 1976, 14: 1663 doi: 10.1103/PhysRevB.14.1663
[24]
Dang X Z, Wang C D, Yu E T, et al. Persistent photoconductivity and defect levels in n-type AlGaN/GaN hetrostructures. Appl Phys Lett, 1998, 72: 2745 doi: 10.1063/1.121077
[25]
Gupta Y, Arun P. Influence of Urbach tail on the refractive index of p-SnS thin films. Phys Status Solidi C, 2017, 14: 1600207
[26]
Tauc J. Absorption edge and internal electric fields in amorphous semiconductors. Mater Res Bull, 1970, 5: 721 doi: 10.1016/0025-5408(70)90112-1
[27]
Brus L E. Electron–electron and electron–hole interactions in small semiconductor crystallites: the size dependence of the lowest excited electronic state. J Chem Phys, 1984, 80: 4403 doi: 10.1063/1.447218
[28]
Sze S M. Physics of semiconductor devices. 2nd ed. John Wiley and Sons, Inc. 1981
[29]
Ran F Y, Xiao Z, Toda Y, et al. n-type conversion of SnS by isovalent ion substitution: Geometrical doping as a new doping route. Sci Rep, 2015, 5: 10428 doi: 10.1038/srep10428
[30]
Gupta Y, Arun P. Influence of strain on the sensitivity of tin sulphide films. Mater Chem Phys, 2017, 191: 86 doi: 10.1016/j.matchemphys.2017.01.029
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    Received: 11 February 2017 Revised: 13 April 2017 Online: Uncorrected proof: 30 October 2017Accepted Manuscript: 13 November 2017Published: 01 November 2017

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      Yashika Gupta, P. Arun. Optimization of SnS active layer thickness for solar cell application[J]. Journal of Semiconductors, 2017, 38(11): 113001. doi: 10.1088/1674-4926/38/11/113001 Y Gupta, P. Arun. Optimization of SnS active layer thickness for solar cell application[J]. J. Semicond., 2017, 38(11): 113001. doi: 10.1088/1674-4926/38/11/113001.Export: BibTex EndNote
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      Yashika Gupta, P. Arun. Optimization of SnS active layer thickness for solar cell application[J]. Journal of Semiconductors, 2017, 38(11): 113001. doi: 10.1088/1674-4926/38/11/113001

      Y Gupta, P. Arun. Optimization of SnS active layer thickness for solar cell application[J]. J. Semicond., 2017, 38(11): 113001. doi: 10.1088/1674-4926/38/11/113001.
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      Optimization of SnS active layer thickness for solar cell application

      doi: 10.1088/1674-4926/38/11/113001
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      • Corresponding author: Email: arunp92@sgtbkhalsa.du.ac.in
      • Received Date: 2017-02-11
      • Revised Date: 2017-04-13
      • Published Date: 2017-11-01

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