Hostname: page-component-586b7cd67f-g8jcs Total loading time: 0 Render date: 2024-12-01T06:55:35.576Z Has data issue: false hasContentIssue false
  • English
  • Français

The effect of active-layer thickness on the characteristic of nanocrystalline silicon thin film transistor

Published online by Cambridge University Press:  31 January 2011

Sun-Jae Kim ,
Sang-Myeon Han ,
Seung-Hee Kuk ,
Jeong-Soo Lee  and
Min-Koo Han
Sun-Jae Kim
Affiliation:
[email protected]@hanmail.net, Seoul National University, School of Electrical Engineering, Seoul, Korea, Republic of
Sang-Myeon Han
Affiliation:
[email protected], Seoul National University, School of Electrical Engineering, Seoul, Korea, Republic of
Seung-Hee Kuk
Affiliation:
[email protected], Seoul National University, School of Electrical Engineering, Seoul, Korea, Republic of
Jeong-Soo Lee
Affiliation:
[email protected], Seoul National University, School of Electrical Engineering, Seoul, Korea, Republic of
Min-Koo Han
Affiliation:
[email protected], Seoul National University, School of Electrical Engineering, Seoul, Korea, Republic of
Get access

Abstract

We fabricated nc-Si TFTs in order to investigate the effect of the active-layer thickness on the characteristic of the nc-Si TFT. Bottom gate nc-Si TFTs were fabricated at 350°C using ICP-CVD. The thicknesses of the nc-Si layer were remained to 700, 1200 and 1700 Å. As the active-layer thickness increases, the mobility and the on-current level were not altered. However, the off-current level increased considerably and on/off ratio decreased. It may be attributed to highly doped characteristic of thick nc-Si film. As the nc-Si film thicker, the conductivity increases considerably and the Fermi level approaches to the conduction band minimum, which indicates the increases of doping level. The oxygen concentration shows high level of unintentional doping. Also, columnar growth of nc-Si film makes that the crystallinity of top region is much higher than that of bottom region. So, the conductivity of thick nc-Si film becomes high compared to that of thin nc-Si film. The structure of the nc-Si TFT with thick nc-Si film can be similar to the serial connection of N+, N- and N+ resistance, so that it suffers difficulty to suppress the off current and to secure high on/off ratio. Therefore, the off current can be suppressed by thinning of the high conducting active nc-Si layer and nc-Si TFT with channel thickness of 700 Å shows good on/off characteristic. It is deduced that bottom gate nc-Si TFT is necessary to have intrinsic channel layer as well as thin channel layer to reduce the leakage current.

Keywords

Sichemical vapor deposition (CVD) (deposition)devices
Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 1153: Symposium A – Amorphous and Polycrystalline Thin Film Silicon Science and Technology–2009 , 2009 , 1153-A21-04
Copyright
Copyright © Materials Research Society 2009

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

1 Lan, J. H. and Kanichi, J. “Planarization of a-Si TFT for High-Aperture-Ratio AMLCDs”, Tech. Digest of Int. Display Res. Conf. 1997, pp. L58–L61, (1997).Google Scholar
2 Im, J. S. and Kim, H. J. “Phase transformation mechanisms involved in excimer laser crystallization of amorphous silicon films”, Appt. Phys. Lett. Vol. 63 (14), pp. 1969–1971, (1993).Google Scholar
3 Itoh, M. Yamamoto, Y. Morita, T. Yoneda, H. Yamane, Y. Tsuchimoto, S. Funada, F. and Awane, K. “High-Resolution Low-Temperature Poly-Si TFT-LCDs Using a Novel Structure with TFT Capacitors”, Tech. Digest of SID 1996, pp17–20, (1996).Google Scholar
4 Ichikawa, K. Suzuki, S. Maino, H. Aoki, T. Higuchi, T. and Oana, Y. “14.3 in.-Diagonal 16-Color TFT-LCD Panel Using a-Si:H TFTs”, Tech. Digest of SID 1999, pp. 226–229, (1989).Google Scholar
5 Hatzopoulos, A. T. Arpatzanis, N. Tassis, D.H. Dimitriadis, C.A. Oudwan, M. Templier, F. and Kamarinos, G. “Study of the Drain Leakage Current in Bottom-Gated Nanocrystalline Silicon Thin-Film Transistors by Conduction and Low-Frequency Noise Measurements Electron Devices”, IEEE Transactions Electron Devices, Vol. 54, (2007).Google Scholar
6 Lee, H. Sazonov, A. and Nathan, A. “Leakage current mechanisms in top-gate nanocrystalline silicon thin film transistors”, Appl. Phys. Lett., Vol.92, (2008).Google Scholar
7 Esmaeili-Rad, M. R., Sazonov, A. and Nathan, A. “High Stability, Low Leakage Nanocrystalline Silicon Bottom Gate Thin Film Transistors for AMOLED Displays”, IEDM 2006, pp. 1–4, (2006).Google Scholar
8 Goto, M. Toyoda, H. Kitagawa, M. Hirao, T. and Sugai, H. “Low Temperature Growth of Amorphous and Polycrystalline Silicon Films from a Modified Inductively Coupled Plasma”, Jpn. J. Appl. Phys. 36, pp. 3714–3720, (1997).Google Scholar
9 Hopwood, J. “Review of inductively coupled”, Plasma Sources Sci. Technol. 1, pp.109–116, (1992).Google Scholar
10 Teng, L. H. and Anderson, W. A. “Thin film transistors on nanocrystalline silicon directly deposited by a microwave plasma CVD”, Solid-State Electronics, Vol 48, pp.309–314, (2004).Google Scholar
11 Platz, R. and Wagner, S. “Intrinsic microcrystalline silicon by plasma-enhanced chemical vapor deposition from dichlorosilane”, Appl. Phys. Lett., Vol. 73, pp.1236–1238, (1998).Google Scholar
12 Torres, P. Meier, J. Fluckiger, R. Krol, U. Anna, J. A. Selvan, Keppner, H. A, Shah, Littlewood, S. D. Kelly, I. E. and Giannoules, P. “Device grade microcrystalline silicon owing to reduced oxygem contamination”, Appl. Phys. Lett., Vol. 69, pp. 1373–1375, (1996).Google Scholar
13 Lee, C. Sazonov, A. and Nathan, A. “High-mobility nanocrystalline silicon thin-film transistors fabricated by plasma-enhanced chemical vapor deposition”, Appl. Phys. Lett., Vol.86, 222106, (2005).Google Scholar