Fabrication, characterization and optimization of high conductivity and high quality nanocrystalline molybdenum thin films

doi:10.1016/j.jmst.2019.05.023

Abstract

Abstract:

The present study investigated the influence of substrate temperature (T_s) and working pressure (P_Ar) on tailoring the properties of nanocrystalline (nc) molybdenum (Mo) films fabricated by radio-frequency magnetron sputtering. The structural, morphological, electrical and optical properties of nc-Mo films were evaluated in detail. The Mo films exhibited (110) orientation with average crystallite size varying from 9 to 22 (±1) nm on increasing T_s. Corroborating with structural data, the electrical resistivity decreased from 55 μΩ cm to 10 μΩ cm, which is the lowest among all the Mo films. For Mo films deposited under variable P_Ar, the (110) peak intensity decrement coupled with peak broadening on increasing P_Ar. Lower deposition pressure yielded densely packed thin films with superior structural properties along with low resistivity of $\widetilde{1}$ 5 μΩ cm. Optimum conditions to produce high quality Mo films with excellent structural, morphological, electrical and optical characteristics for utilization in solar cells as back contact layers were identified.

Key words: Molybdenum, Thin films, Microstructure, Electrical characteristics, Optical properties, Solar cells

Anil K.Battu, Nanthakishore Makeswaran, C.V. Raman. Fabrication, characterization and optimization of high conductivity and high quality nanocrystalline molybdenum thin films[J]. J. Mater. Sci. Technol., 2019, 35(11): 2734-2741.

Figures/Tables 11

Table 1 Experimental conditions employed for Mo film deposition.

Parameter	Value
Base pressure	2?×?10^-7 Torr
Sputtering power	100 W
Argon sputtering pressure	3-25 mTorr (T_s?=?200?°C, constant)
Deposition temperature	25-500?°C (P_Ar?=?5 mTorr, constant)
Target-to-substrate distance	7 cm
Substrate	Silicon (100)
Film thickness	$\widetilde{1}$05?±?5?nm

Fig. 1. (a) GIXRD patterns of Mo films deposited at various Ts and (b) high-resolution scans of the Mo (110). The peak observed at $\widetilde{4}$ 0.5° corresponds to diffraction from (110) crystal planes of body centered cubic (bcc) Mo. The (110) peak intensity increase with increasing Ts can be noted and the peak sharpens with a decrease in full width at half maxima (FWHM) with increasing Ts. In addition, a slight positive peak shift occurs with increasing Ts.

Fig. 2. Variation of average crystallite size and lattice strain of Mo films with Ts.

Fig. 3. Top-view SEM images of Mo films deposited under variable Ts.

Fig. 4. Electrical characteristics of Mo films sputtered at different Ts: (a) electrical resistivity; (b) carrier mobility; (c) carrier concentration with Ts. It is evident that the electrical characteristics are strongly influenced by the deposition temperature.

Fig. 5. Optical reflectance of Mo films deposited under variable Ts.

Fig. 6. GIXRD patterns of Mo films deposited at various PAr: (a) high resolution scan of Mo (110) peak; (b) lattice strain; (c) full width at half maximum of (110) peak.

Fig. 7. SEM images of Mo films deposited under variable PAr.

Fig. 8. Interface microstructure evolution in Mo films deposited under variable PAr.

Fig. 9. Electrical characteristics of Mo films sputtered at different PAr: (a) electrical resistivity; (b) carrier mobility; (c) carrier concentration. It is evident that the electrical characteristics are strongly influenced by the deposition pressure.

Fig. 10. Optical reflectance of Mo films as a function of PAr.

References

[1]	N. Dhar, P. Chelvanathan, M. Zaman, K. Sopian, N. Amin,Energy Proc., 33 (2013), 186-197.
[2]	N. Akcay, N.A. Sonmez, E. Zaretskaya, S. Ozcelik, Curr. Appl. Phys., 18 (2018), 491-499.
[3]	M. Jubault, L. Ribeaucourt, E. Chassaing, G. Renou, D. Lincot, F. Donsanti, Sol. Energy Mater. Sol. Cells, 95 (2011), pp. S26-S31.
[4]	S. De Wolf, A. Descoeudres, Z.C. Holman, C. Ballif, Green, 2 (2012), 7-24.
[5]	Z.H. Li, E.S. Cho, S.J. Kwon, Appl. Surf. Sci., 257 (2011), 9682-9688.
[6]	X. Xu, S. Li, J. Chen, S. Cai, Z. Long, X. Fang, Adv. Funct. Mater. 28 (2018), 18020291.
[7]	X. Fang, L. Zhang, J. Mater. Sci.Technol. 22 (2006) 1-18.
[8]	M.R. Leyden, L. Meng, Y. Jiang, L.K. Ono, L. Qiu, E.J. Juarez-Perez, C. Qin, C. Adachi, Y. Qi, J. Phys. Chem. Lett. 8 (2017) 3193-3198.
[9]	W. Yang, K. Hu, F. Teng, J. Weng, Y. Zhang, X. Fang, Nano Lett. 18 (2018)4697-4703.
[10]	D. Li, X. Shu, D. Kong, H. Zhou, Y. Chen, J. Mater. Sci.Technol. 34 (2018)2027-2034.
[11]	X. Mathew, J.P. Enriquez, A. Romeo, A.N. Tiwari, Sol. Energy 77 (2004)831-838.
[12]	J.H. Yoon, S. Cho, W.M. Kim, J.K. Park, Y.J. Baik, T.S. Lee, T.Y. Seong, J.H. Jeong,Sol. Energy Mater. Sol. Cells 95 (2011) 2959-2964.
[13]	P.C. Huang, C.H. Huang, M.Y. Lin, C.Y. Chou, C.Y. Hsu, C.G. Kuo, Int. J.Photoenergy 2013 (2013) 1-8.
[14]	Z.H. Li, E.S. Cho, S.J. Kwon, Appl. Surf. Sci. 257 (2011) 9682-9688.
[15]	J.H. Cha, K. Ashok, N.J.S. Kissinger, Y.H. Ra, J.K. Sim, J.S. Kim, C.R. Lee, J. KoreanPhys.Soc. 59 (2011) 2280-2285.
[16]	X. Dai, A. Zhou, L. Feng, Y. Wang, J. Xu, J. Li, Thin Solid Films 567 (2014) 64-71.
[17]	H. Khatri, S. Marsillac,J. Phys. Condens.Matter 20 (2008), 055206.
[18]	G. Zoppi, N.S. Beattie, J.D. Major, R.W. Miles, I. Forbes, J. Mater. Sci. 46 (2011)4913-4921.
[19]	J. van Deelen, C. Frijters, Sol. Energy 143 (2017) 93-99.
[20]	P. Sinsermsuksakul, K. Hartman, S.B. Kim, J. Heo, L. Sun, H.H. Park, R. Chakraborty, T. Buonassisi, R.G. Gordon,Appl. Phys. Lett. 102 (2013), 053901.
[21]	J.H. Scofield, A. Duda, D. Albin, B. Ballard, P. Predecki, Thin Solid Films 260 (1995) 26-31.
[22]	D.W. Hoffman, J.A. Thornton, J. Vac. Sci.Technol. 20 (1982) 355-358.
[23]	J.J. Scragg, J.T. Watjen, M. Edoff, T. Ericson, T. Kubart, C. Platzer-Bj?rkman, J.Am. Chem.Soc. 134 (2012) 19330-19333.
[24]	K. Orgassa, H.W. Schock, J. Werner, Thin Solid Films 431 (2003)387-391.
[25]	J. Bartolome, M. Diaz, J. Requena, J. Moya, A. Tomsia, Acta Mater. 47 (1999)3891-3899.
[26]	T. Wada, N. Kohara, S. Nishiwaki, T. Negami, Thin Solid Films 387 (2001)118-122.
[27]	R. Tran, Z. Xu, N. Zhou, B. Radhakrishnan, J. Luo, S.P. Ong, Acta Mater. 117 (2016) 91-99.
[28]	G. Martinez, C.V. Ramana, AIP Adv. 7 (2017) 1-8.
[29]	K.S. Harsha, Principles of Vapor Deposition of Thin Films, Elsevier, 2015.
[30]	P.G. Dubey, J. Manandhar, S. Shutthanandan, V. Ramana, Sol. Energy 166 (2018) 146-158.
[31]	B.S. Yadav, A.C. Badgujar, S.R. Dhage, Sol. Energy 157 (2017) 507-513.
[32]	K.H. Ong, R. Agileswari, B. Maniscalco, P. Arnou, C.C. Kumar, J.W. Bowers, M.B. Marsadek, Int. J. Photoenergy 33 (2018) 723-729.
[33]	K.A. Kress, G.J. Lapeyre, J. Opt. Soc.Am. 60 (1970) 1681-1684.
[34]	D. Guo, Z. Wu, Y. An, X. Li, X. Guo, X. Chu, C. Sun, M. Lei, L. Li, L. Cao, J. Mater.Chem. C 3 (2015) 1830-1834.
[35]	X. Jia, Z. Lin, T. Yang, B. Puthen-Veettil, L. Wu, G. Conibeer, I. Perez-Wurfl,Appl. Sci. 8 (2018) 1692.
[36]	P. Bommersbach, L. Arzel, M. Tomassini, E. Gautron, C. Leyder, M. Urien, D.Dupuy, N. Barreau, Prog. Photovolt. 21 (2013) 332-343.
[37]	M. Theelen, F. Daume, Sol. Energy 133 (2016) 586-627.
[38]	D. Fernández-González, í. Ruiz-Bustinza, C. González-Gasca, J.P. Noval, J.Mochón-Casta $\widetilde{n}$os, J. Sancho-Gorostiaga, L.F. Verdeja, Sol. Energy 170 (2018)520-540.
[39]	J. Waldron, D. Juenker, J. Opt. Soc.Am. 54 (1964) 204-207.
[40]	J.H. Yoon, S. Cho, W.M. Kim, J.K. Park, Y.J. Baik, T.S. Lee, T.Y. Seong, J.H. Jeong,Sol. Energy Mater. Sol. Cells 95 (2011) 2959-2964.
[41]	S. Wang, C. Hsu, F. Shiou, P. Huang, D. Wen, J. Korean Inst.Electr. Electron.Mater. Eng. 42 (2013) 71-77.
[42]	R. Zhang, Z. Huo, X. Jiao, B. Du, H. Zhong, Y. Shi, J. Nanosci. Nanotechnol. 16 (2016) 8154-8159.
[43]	B. Cullity, Elements of X-ray Diffraction, Addison-Wesley Publishing Co., Inc.,USA, 1956, p. 78.
[44]	S. Thirumavalavan, Y. Mani, S.S. Suresh, J. Nano-Electron.Phys. 7 (2015)040241-040244.
[45]	H. Ahn, D. Lee, Y. Um, Appl. Sci. Converg. Technol. 26 (2017) 11-15.
[46]	J.H. Yoon, K.H. Yoon, W.M. Kim, J.K. Park, Y.J. Baik, T.Y. Seong, J.H. Jeong,J. Phys.D 44 (2011), 4253021.
[47]	W. Li, X. Yan, A.G. Aberle, S. Venkataraj,J. Appl. Phys. 54 (2015), 08KC141.
[48]	S. Siol, T.P. Dhakal, G.S. Gudavalli, P.P. Rajbhandari, C. DeHart, L.L. Baranowski,A. Zakutayev, ACS Appl. Mater. Interf. 8 (2016) 14004-14011.
[49]	L. Krusin-Elbaum, M. Aboelfotoh, T. Lin, K. Ahn, Thin Solid Films 153 (1987)349-358.
[50]	Y.C. Lin, W. Yen, L. Wang, Chin. J. Phys. 50 (2012) 82-88.
[51]	A.K. Battu, V.B. Zade, E. Deemer, C.V. Ramana,Adv. Eng. Mater. 20 (2018),18004961.
[52]	D. Zhou, H. Zhu, X. Liang, C. Zhang, Z. Li, Y. Xu, J. Chen, L. Zhang, Y. Mai, Appl.Surf. Sci. 362 (2016) 202-209.