Over the last few decades, 1D semiconducting silicon-nanowires (SiNWs) have been widely investigated as potential building blocks for future electronic devices because of their excellent electrical performance compared with bulk silicon, small sizes, and controllable bottom-up fabrications [1]. Many groups have demonstrated promising biosensor applications of SiNW-based field effect transistors (FETs) [2]. Recently Weber et al. have reported dopant-free Shottky barrier (SB) FETs consisting of intrinsic SiNWs working as a channel and NiSi2 nanowires working as source and drain contacts with gate lengths down to sub-photolithographic values [3]. Measurements of their transport characteristics have shown the highest on-current and on-conductance values recorded to date for intrinsic SiNW-FETs [4]. These SiNW-based SB-FETs are also expected to provide promising platforms for biosensor applications. In this work, we have developed a multi-scaled theoretical framework for the study of biosensors consisting of the intrinsic SiNW-based SB-FETs and biomolecules (receptors) covering the surface of the SiNWs. The aim of our study is to investigate the changes in the current through the SB-FETs in response to the binding of the ligands to the bio-receptors attached on the surface of the SiNWs. For this purpose, we have combined two approaches in different scales: one is a classical 1D-tunneling problem at the Si/NiSi2 interfaces in SB-FETs and another is the calculation of the electrostatic perturbation due to the biomolecules (receptors) attached on the surface of the NWs in atomistic scale using density functional theory. As a first step, in order to understand the basic charge transport characteristics though the SiNWs, we have modeled pristine SiNW-based SB-FETs consisting of an intrinsic SiNW working as a channel and NiSi2 NWs working as source and drain without the biomolecules. We have calculated the electrostatic potential profiles across the Si/NiSi2 interfaces with different gate lengths and gate voltages. Then we analyzed the influence of the gate lengths and the gate voltages on the charge tunneling through the SB-FETs. In addition, we have analyzed how the length dependence of the conductance in the SiNW-SB-FETs relates with the Anderson localization regime [5].
References:
[1] R. Rurali, Rev. Mod. Phys. 82, 427 (2010).
[2] Y. Cui, Z. Zhong, D. Wang, W. U. Wang, and C. M. Lieber, Nano Lett. 3, 149 (2003).
[3] W. M. Weber, L. Geelhaar, A. P. Graham, E. Unger, G. S. Duesberg, M. Liebau, W. Palmer, C. Cheze, H. Riechert, P. Lugli, and F. Kreupl, Nano Lett. 6, 2660 (2006).
[4] W. M. Weber, L. Geelhaar, E. Unger, C. Cheze, F. Kreupl, H. Riechert, and P. Lugli, Phys. Stat. Sol. (b) 244, 4170 (2007).
[5] C. Gomez-Navarro, P. J. de Pablo, J. Gomez-Herrero, B. Biel, F. J. Garcia-Vidal, A. Rubio, and F. Flores, Nature Materials 4, 534 (2005).
Over the last few decades, 1D semiconducting silicon-nanowires (SiNWs) have been widely investigated as potential building blocks for future electronic devices because of their excellent electrical performance compared with bulk silicon, small sizes, and controllable bottom-up fabrications [1]. Many groups have demonstrated promising biosensor applications of SiNW-based field effect transistors (FETs) [2]. Recently Weber et al. have reported dopant-free Shottky barrier (SB) FETs consisting of intrinsic SiNWs working as a channel and NiSi2 nanowires working as source and drain contacts with gate lengths down to sub-photolithographic values [3]. Measurements of their transport characteristics have shown the highest on-current and on-conductance values recorded to date for intrinsic SiNW-FETs [4]. These SiNW-based SB-FETs are also expected to provide promising platforms for biosensor applications. In this work, we have developed a multi-scaled theoretical framework for the study of biosensors consisting of the intrinsic SiNW-based SB-FETs and biomolecules (receptors) covering the surface of the SiNWs. The aim of our study is to investigate the changes in the current through the SB-FETs in response to the binding of the ligands to the bio-receptors attached on the surface of the SiNWs. For this purpose, we have combined two approaches in different scales: one is a classical 1D-tunneling problem at the Si/NiSi2 interfaces in SB-FETs and another is the calculation of the electrostatic perturbation due to the biomolecules (receptors) attached on the surface of the NWs in atomistic scale using density functional theory. As a first step, in order to understand the basic charge transport characteristics though the SiNWs, we have modeled pristine SiNW-based SB-FETs consisting of an intrinsic SiNW working as a channel and NiSi2 NWs working as source and drain without the biomolecules. We have calculated the electrostatic potential profiles across the Si/NiSi2 interfaces with different gate lengths and gate voltages. Then we analyzed the influence of the gate lengths and the gate voltages on the charge tunneling through the SB-FETs. In addition, we have analyzed how the length dependence of the conductance in the SiNW-SB-FETs relates with the Anderson localization regime [5].
References:
[1] R. Rurali, Rev. Mod. Phys. 82, 427 (2010).
[2] Y. Cui, Z. Zhong, D. Wang, W. U. Wang, and C. M. Lieber, Nano Lett. 3, 149 (2003).
[3] W. M. Weber, L. Geelhaar, A. P. Graham, E. Unger, G. S. Duesberg, M. Liebau, W. Palmer, C. Cheze, H. Riechert, P. Lugli, and F. Kreupl, Nano Lett. 6, 2660 (2006).
[4] W. M. Weber, L. Geelhaar, E. Unger, C. Cheze, F. Kreupl, H. Riechert, and P. Lugli, Phys. Stat. Sol. (b) 244, 4170 (2007).
[5] C. Gomez-Navarro, P. J. de Pablo, J. Gomez-Herrero, B. Biel, F. J. Garcia-Vidal, A. Rubio, and F. Flores, Nature Materials 4, 534 (2005).
