Analysis of electrical parameters of organic thin film transistors based on thickness variation in semi-conducting and dielectric layers

Brijesh Kumar; Brajesh Kumar Kaushik; Yuvraj Singh Negi

Analysis of electrical parameters of organic thin film transistors based on thickness variation in semi-conducting and dielectric layers

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Author(s): Brijesh Kumar ^{1, 2} ; Brajesh Kumar Kaushik ² ; Yuvraj Singh Negi ¹
- Affiliations: 1: Department of Polymer and Process Engineering, Indian Institute of Technology Roorkee – 247667, Uttarakhand, India;
  2: Department of Electronics and Communication Engineering, Indian Institute of Technology Roorkee – 247667, Uttarakhand, India
Source: Volume 8, Issue 2, March 2014, p. 131 – 140
DOI: 10.1049/iet-cds.2013.0275 , Print ISSN 1751-858X, Online ISSN 1751-8598

Received 19/07/2013, Accepted 06/11/2013, Revised 13/10/2013, Published 27/01/2014

This research study analyses the impact of semi-conductor (t _osc) and dielectric (t _ox) thicknesses on top contact (TC) and bottom contact (BC) organic thin film transistors (OTFTs) using Atlas 2-D numerical device simulation. Thickness of each layer is varied from 20 to 150 nm. The parameters such as electric field, charge carrier distribution and trap density are analysed from device physics point of view with variations in organic semi-conductor layer and dielectric thicknesses. A decrease of 22% in TC to BC current ratio is observed for maximum increase in t _osc, whereas, it remains almost constant at unity with variations in t _ox. Furthermore, the maximum mobility for TC is achieved at t _osc of 20 nm and reduces monotonically with further increase in thickness because of lowering of average charge. However, its highest value is obtained at 60 nm for BC structure that declines with positive or negative change in t _osc. Besides this, the threshold voltage (V _t) shows a reduction of 50% for both the structures on scaling down t _ox from 150 to 20 nm. Furthermore, the ON to OFF current ratio is found to be more dependent on t _osc as compared with t _ox. This is because of a dominant impact of t _osc reduction on OFF current as compared with impact of t _ox reduction on the ON current. Additionally, a decrease in contact resistance (R _C) is observed in TC structure for thicker active layer while operating at lower V_gs . However, at high gate voltage, t _osc maps to the access resistance that results in higher R _C values.

References

1. 1)
  - 28. Kirova, N., Bussac, M.N.: ‘Self-trapping of electrons at the field-effect junction of a molecular crystal’, Phys. Rev. B, 2003, 68, (23), pp. 235312-1–235312-6 (doi: 10.1103/PhysRevB.68.235312).
2. 2)
  - 25. Ha, T.J., Sparrowe, D., Dodabalapur, A.: ‘Device architectures for improved amorphous polymer semiconductor thin film transistors’, Org. Electron., 2011, 12, (11), pp. 1846–1851 (doi: 10.1016/j.orgel.2011.07.014).
3. 3)
  - 32. Jia, H., Gowrisankar, S., Pant, G.K., Wallace, R.M., Gnade, B.E.: ‘Effect of poly (3-hexaylthiophene) film thickness on organic thin film transistor properties’, J. Vac. Sci. Technol. A, 2006, 24, (4), pp. 1228–1232 (doi: 10.1116/1.2202858).
4. 4)
  - M. Estrada , A. Cerdeira , J. Puigdollers . Accurate modeling and parameter extraction method for organic TFTs. Solid-State Electron. , 1009 - 1016
5. 5)
  - 17. Klauk, H., Zschieschang, U., Halik, M.: ‘Low voltage organic thin film transistors with large transconductance’, J. Appl. Phys., 2007, 102, (7), pp. 074514-1–075514-7 (doi: 10.1063/1.2794702).
6. 6)
  - 3. Lee, J.B., Subramanian, V.: ‘Weave patterned organic transistors on fiber for e-textiles’, IEEE Trans. Electron. Devices, 2005, 52, (2), pp. 269–275 (doi: 10.1109/TED.2004.841331).
7. 7)
  - 15. Islam, M.N.: ‘Impact of film thickness of organic thickness on off state current of organic thin film transistors’, J. Appl. Phys., 2011, 110, (11), pp. 114906-1–114906-10.
8. 8)
  - 9. Guerin, M., Daami, A., Jacob, S., et al: ‘High-gain fully printed organic complementary circuits on flexible plastic foils’, IEEE Trans. Electron. Devices, 2011, 58, (10), pp. 3587–3593 (doi: 10.1109/TED.2011.2162071).
9. 9)
  - 34. Cosseddu, P., Bonfiglio, A.: ‘A comparison between bottom contact and top contact all organic field effect transistors assembled by soft lithography’, Thin Solid Films, 2007, 515, (19), pp. 7551–7555 (doi: 10.1016/j.tsf.2006.11.182).
10. 10)
  - 36. Natali, D., Fumagalli, L., Sampietro, M.: ‘Modeling of organic thin film transistors: effect of contact resistances’, J. Appl. Phys., 2007, 101, (1), pp.|p 014501-1–014501-12 (doi: 10.1063/1.2402349).
11. 11)
  - 2. Moore, S.K.: ‘Just one word – plastics’, IEEE Spectr., 2002, 39, (9), pp. 55–59 (doi: 10.1109/MSPEC.2002.1030969).
12. 12)
  - 41. Tiwari, S.P., Namdas, E.B., Rao, V.R., Fichou, D., Mhaisalkar, S.G.: ‘Solution processed n-type organic field-effect transistors with high on/off current ratios based on fullerene derivatives’, IEEE Electron. Device Lett., 2007, 28, (10), pp. 880–883 (doi: 10.1109/LED.2007.905960).
13. 13)
  - 19. Chiang, C.S., Martin, S., Kanicki, J., Ugai, Y., Yukawa, T., Takeuchi, S.: ‘Top gate staggered amorphous silicon thin ﬁlm transistors: series resistance and nitride thickness effects’, Jpn. J. Appl. Phys., 1998, 37, (11), pp. 5914–5920 (doi: 10.1143/JJAP.37.5914).
14. 14)
  - 29. Hulea, I.N., Fratini, S., Xie, H., et al: ‘Tunable Frohlich polarons in organic single crystal transistors’, Nat. Mater., 2006, 5, pp. 982–986 (doi: 10.1038/nmat1774).
15. 15)
  - 30. Blanchet, G.B., Fincher, C.R., Lefenfeld, M., Rogers, J.A.: ‘Contact resistance in organic thin ﬁlm transistors’, Appl. Phys. Lett., 2004, 84, (2), pp. 296–298 (doi: 10.1063/1.1639937).
16. 16)
  - 27. Pernstich, K.P., Haas, S., Oberhoff, D., et al: ‘Threshold voltage shift in organic field effect transistors by dipole monolayers on the gate insulator’, J. Appl. Phys., 2004, 96, (11), pp. 6431-1–6431-8 (doi: 10.1063/1.1810205).
17. 17)
  - 37. Bullejos, P.L., Tejada, J.A.J., Bolivar, S.R., Deen, M.J., Marinov, O.: ‘Model for the injection of charge through the contacts of organic transistors’, J. Appl. Phys., 2009, 105, (8), pp. 084516-1–084516-8.
18. 18)
  - 11. Gupta, D., Hong, Y.: ‘Understanding the effect of semiconductors thickness on device characteristics in organic thin film transistors by way of two dimensional simulations’, Org. Electron., 2010, 11, (1), pp. 127–136 (doi: 10.1016/j.orgel.2009.10.009).
19. 19)
  - 12. Kano, M., Minari, T., Tsukagoshi, K., Maeda, H.: ‘Control of device parameters by active layer thickness in organic thin film transistors’, Appl. Phy. Lett., 2011, 98, (7), pp. 073307-1–073307-3 (doi: 10.1063/1.3555463).
20. 20)
  - 40. Kumar, B., Kaushik, B.K., Negi, Y.S., Saxena, S., Varma, G.D.: ‘Analytical modeling and parameter extraction of top and bottom contact structures of organic thin film transistors’, Microelectron. J., 2013, 44, (9), pp. 736–143 (doi: 10.1016/j.mejo.2013.06.004).
21. 21)
  - 24. Gupta, D., Katiyar, M., Gupta, D.: ‘An analysis of the difference in behavior of top and bottom contact organic thin film transistors using device simulation’, Org. Electron., 2009, 10, (5), pp. 775–784 (doi: 10.1016/j.orgel.2009.03.012).
22. 22)
  - 14. Marinov, O., Deen, M.J., Iniguez, B., Ong, B.: ‘Charge localization in polymeric metal-oxide semiconductor capacitors’, J. Vac. Sci. Technol. A, 2006, 24, (3), pp. 649–653 (doi: 10.1116/1.2172929).
23. 23)
  - 16. Mariucci, L., Simeone, D., Cipolloni, S., et al: ‘Effect of active layer thickness on electrical characteristics of pentacene TFTs with PMMA buffer layer’, Solid State Electron., 2008, 52, (3), pp. 412–416 (doi: 10.1016/j.sse.2007.10.010).
24. 24)
  - 13. Verilhac, J.M., Benwadih, M., Altazin, S., et al: ‘Effects of amorphous semiconductor thickness on top gate staggered organic field-effect transistors’, Appl. Phys. Lett., 2009, 94, (14), pp. 143301-1–143301-3 (doi: 10.1063/1.3111446).
25. 25)
  - 8. Takamiya, M., Sekitani, T., Kato, Y., Kawaguchi, H., Someya, T., Sakurai, T.: ‘An organic FET SRAM with back gate to increase static noise margin and its application to braille sheet display’, IEEE J. Solid State Circuits, 2007, 42, (1), pp. 93–100 (doi: 10.1109/JSSC.2006.886578).
26. 26)
  - 23. Gupta, D., Jeon, N., Yoo, S.: ‘Modeling the electrical characteristics of TIPS-pentacene thin film transistors: effect of contact barrier, field-dependent mobility and traps’, Org. Electron., 2008, 9, (6), pp. 1026–1031 (doi: 10.1016/j.orgel.2008.08.005).
27. 27)
  - 31. Shekar, B.C., Lee, J., Rhee, S.W.: ‘Organic thin film transistors: materials, processes and devices’, Korean J. Chem. Eng., 2004, 21, (1), pp. 267–287 (doi: 10.1007/BF02705409).
28. 28)
  - 18. Wang, H., Li, L., Ji, Z., et al: ‘Contact length dependent contact resistance of top gate staggered organic thin film transistors’, IEEE Electron. Device Lett., 2013, 34, (1), pp. 69–71 (doi: 10.1109/LED.2012.2224631).
29. 29)
  - 6. Cantatore, E., Geuns, T.C.T., Gelinck, G.H., et al: ‘A 13.56 MHz RFID system based on organic transponders’, IEEE J. Solid State Circuits, 2007, 42, (1), pp. 84–92 (doi: 10.1109/JSSC.2006.886556).
30. 30)
  - 5. Mizukami, M., Hirohata, N., Iseki, T., et al: ‘Flexible AM OLED panel driven by bottom contact OTFTs’, IEEE Electron. Device Lett., 2006, 27, (4), pp. 249–251 (doi: 10.1109/LED.2006.870413).
31. 31)
  - 1. Kim, Y.H., Moon, D.G., Han, J.I.: ‘Organic TFT array on a paper substrate’, IEEE Electron. Device Lett., 2004, 25, (10), pp. 702–704 (doi: 10.1109/LED.2004.836502).
32. 32)
  - 20. ATLAS user's manual, device simulation software. Santa Clara, Silvaco International, 2012.
33. 33)
  - L. Burgi , T. Richards , R. Friend , H. Sirringhaus . Close look at charge carrier injection in polymer field-effect transistors. J. Appl. Phys. , 9 , 6129 - 6137
34. 34)
  - 42. Kumar, B., Kaushik, B.K., Negi, Y.S.: ‘Modeling of top and bottom contact structure organic field effect transistors’, J. Vac. Sci. Technol. B, 2013, 31, (1), pp. 012401-1–012401-7 (doi: 10.1116/1.4773054).
35. 35)
  - C.H. Shim , F. Maruoka , R. Hattori . Structural analysis on organic thin-film transistor with device simulation. IEEE Trans. Electron Devices
36. 36)
  - 10. Resendiz, L., Estrada, M., Cerdeira, A., Iniguez, B., Deen, M.J.: ‘Effect of active layer thickness on the electrical characteristics of polymer thin film transistors’, Org. Electron., 2010, 11, (9), pp. 1920–1927 (doi: 10.1016/j.orgel.2010.09.002).
37. 37)
  - H. Klauk , M. Halik , U. Zschiescahng , F. Eder , G. Schmid , C. Dehm . Pentacene organic transistors and ring oscillators on glass and on flexible polymeric susbtrates. Appl. Phys. Lett.
38. 38)
  - 7. Brianda, D., Opreab, A., Courbata, J., Barsanb, N.: ‘Making environmental sensors on plastic foils-Review article’, Mater. Today, 2011, 14, (9), pp. 416–423 (doi: 10.1016/S1369-7021(11)70186-9).
39. 39)
  - 26. Deen, M.J., Marinov, O., Zschieschang, U., Klauk, H.: ‘Organic thin ﬁlm transistors: Part II – Parameter extraction’, IEEE Trans. Electron. Devices, 2009, 56, (12), pp. 2962–2968 (doi: 10.1109/TED.2009.2033309).
40. 40)
  - 39. Necliudovc, P.V., Shur, M.S., Gundlach, D.J., Jackson, T.N.: ‘Contact resistance extraction in pentacene thin film transistors’, Solid-State Electron., 2003, 47, (2), pp. 259–262 (doi: 10.1016/S0038-1101(02)00204-6).

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Analysis of electrical parameters of organic thin film transistors based on thickness variation in semi-conducting and dielectric layers

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