09:45 〜 10:00
▲ [15a-513-4] First-principles study of inter-band tunnelling current through co-dopants in Si Nano-pn Tunnel Diodes
キーワード：Silicon Nano-Tunnel diode, Co-dopants, Tunneling current
As the Tunnelling Field Effect Transistor (TFET) overcomes the subthreshold slope thermal limitation of MOSFETs, they are a potential successor of MOSFETs [1]. Moreover silicon-based TFETs are the most attractive because of the well-established silicon technology. However, band-to-band tunneling (BTBT) in Si requires assistance of phonons for momentum conservation due to its indirect bandgap characteristics. Recently, isoelectronic traps (IETs) showed the incrase in the inter-band tunneling current without phonon assistance [2]. In this research work, we report the role of co-dopants at the p-to-n interface of the tunnel diode in the tunneling current enhancement without any phonon assitance. These results are based on the first-principles simulations in comparison with our experimental results for nano-pn tunnel diodes [3].
To carry out realistic device simulation, atomistic structure of the simulated device is constructed with p- and n-type regions with the doping concentration of 5x1019 cm-3 (Fig. 1(a)). In the thin central intrinsic Si region, single P and B dopants are placed. The uniform bulk doping in the regions away from the depletion region was realized by using the atomic compensation technique [4-5]. These devices exhibit typical Esaki-diode negative differential conductance (NDC) behaviours. Moreover, we noticed a remarkable current increase by four orders of magnitude for (100) Si channel with a P-B pair placed 1.3 nm apart as compared to no discrete dopants in the depletion region (Fig. 1(b)). When the single dopants were placed at optimized distance from the uniformly doped bulk regions then energy states are created in the depletion region of the tunnel diode. This leads to an increase in the inter-band tunnelling current. These results illustrate the impact of individual dopants in the depletion region and provide pathways to increase the inter-band tunnelling in nano-pn tunnel diodes. Detailed discussion of nano-pn diode with different crystal orientation, dopant positions and I-V characteristics will be given in the conference presentation.
References:
[1] A. M. Ionescu et.al., Nature 479.7373 (2011): 329-337. [2] T. Mori et al., Appl. Phys. Lett. 106, 083501 (2015). [3] M. Tabe et.al., Applied Physics Letters 108.9 (2016): 093502. [4] M. Brandbyge et.al., Physical Review B 65.16 (2002): 165401. [5] Atomistix ToolKit QuantumWise
To carry out realistic device simulation, atomistic structure of the simulated device is constructed with p- and n-type regions with the doping concentration of 5x1019 cm-3 (Fig. 1(a)). In the thin central intrinsic Si region, single P and B dopants are placed. The uniform bulk doping in the regions away from the depletion region was realized by using the atomic compensation technique [4-5]. These devices exhibit typical Esaki-diode negative differential conductance (NDC) behaviours. Moreover, we noticed a remarkable current increase by four orders of magnitude for (100) Si channel with a P-B pair placed 1.3 nm apart as compared to no discrete dopants in the depletion region (Fig. 1(b)). When the single dopants were placed at optimized distance from the uniformly doped bulk regions then energy states are created in the depletion region of the tunnel diode. This leads to an increase in the inter-band tunnelling current. These results illustrate the impact of individual dopants in the depletion region and provide pathways to increase the inter-band tunnelling in nano-pn tunnel diodes. Detailed discussion of nano-pn diode with different crystal orientation, dopant positions and I-V characteristics will be given in the conference presentation.
References:
[1] A. M. Ionescu et.al., Nature 479.7373 (2011): 329-337. [2] T. Mori et al., Appl. Phys. Lett. 106, 083501 (2015). [3] M. Tabe et.al., Applied Physics Letters 108.9 (2016): 093502. [4] M. Brandbyge et.al., Physical Review B 65.16 (2002): 165401. [5] Atomistix ToolKit QuantumWise