| AVS 63rd International Symposium & Exhibition | |
| Electronic Materials and Photonics | Friday Sessions |
| Session EM-FrM |
| Session: | Late Breaking News on Electronic Materials and Devices |
| Presenter: | Manoharan Muruganathan, Japan Advanced Institute of Science and Technology, Japan |
| Authors: | M. Muruganathan, Japan Advanced Institute of Science and Technology, Japan D. Moraru, Research Institute of Electronics, Shizuoka University M. Tabe, Research Institute of Electronics, Shizuoka University H. Mizuta, Japan Advanced Institute of Science and Technology, Japan |
| Correspondent: | Click to Email |
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, a large bandgap in silicon results in a small band-to-band-tunnelling efficiency, hence low on-current. In order to improve the on-current, fundamental study of atomistic pn tunnel diode is an imperative step. Here, we report that inter-band tunnelling current can be enhanced by the resonance of deepened energy levels of discrete dopants. Number and position of dopants at the pn junction interface play a crucial role in enhancing the inter-band tunnelling current. These results are based on the first-principles simulations in comparison with our experimental results for nano-pn tunnel diodes [2].
Our simulated atomistic structure consists of p- and n-type electrodes, which are highly doped with doping concentration similar to the experimental levels and a thin central intrinsic Si channel that corresponds to the depletion region. As realized in the fabricated devices, single P and B dopants are placed in the intrinsic Si channel the depletion region. The uniform bulk doping in the regions away from the depletion region was realized by using the atomic compensation technique [3-4]. We noticed a remarkable current increase by four orders of magnitude for the device with a P-B pair placed 1.3 nm apart as compared to no discrete dopants in the depletion region. This is due to the energy levels created by the P-B pair in the depletion region and their matching to the electrode energy levels when the bias voltage is changed. Moreover, these devices exhibit typical Esaki-diode negative differential conductance (NDC) behaviours as well. When the single dopants were placed nearer to the uniformly doped bulk regions then well aligned energy levels were formed in the depletion region. This leads to an increase in the inter-band tunnelling current. If the number of single dopants in the depletion region is increased then we have more induced states in the depletion region, which also helps to increase 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.
References:
[1] A. M. Ionescu et.al., Nature 479.7373 (2011): 329-337.
[2] M. Tabe et.al., Applied Physics Letters 108.9 (2016): 093502.
[3] M. Brandbyge et.al., Physical Review B 65.16 (2002): 165401.
[4] Atomistix ToolKit version 2015.1, QuantumWise A/S www.quantumwise.com.