The Effect of Temperature in a thin Si Nanowire Transistor, with a Single Donor in the Channel, using Dissipative Physic
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The Effect of Temperature in a thin Si Nanowire Transistor, with a Single Donor in the Channel, using Dissipative Physics Antonio Martinez, Karol Kalna and Manuel Aldegunde Electronic Systems Design Centre, College of Engineering, Swansea University, Singleton Park, Swansea, SA2 8PY,Wales, UK. ABSTRACT Dissipative quantum transport simulations using the Non-Equilibrium Green Function Formalism have been carried out to obtain a transfer characteristic of a Si gate-all-around (GAA) nanowire transistor. A donor-type impurity has been located close to the source/channel interface, creating a resonant level. The existence and energy of the resonant level depends on the value of the gate bias. The dependence of the current reduction due to phonon scattering as a function of the gate bias, has a minimum due to the resonant level. The simulations at different temperatures have shown a decline in the sub-threshold slope at high temperature and an improvement at low temperature. Finally, the sub-threshold slope approximate follows the standard linear temperature dependence. INTRODUCTION Non-planar architectures such as FinFETs with improved electrostatic control and Ion/Ioff ratio have created new pathways for miniaturization in CMOS technology. Nanowire transistors remain potential candidates for future CMOS applications but their integration into fabrication is still a challenging problem. Nevertheless, individual Si nanowire transistors down to a 2nm diameter have been successfully fabricated. An on-going problem in small nanostructures is the control of the dopant position. In large devices, the exact position and the electrical potential around a single dopant play a negligible role in the current-voltage characteristic. However, for devices of nanometer dimensions, a small amount of dopants can be found in the active region of the device and the current voltage characteristic is very sensitive to the number and spatial configuration of dopants in the device. Just one or two dopants can be found in the channel of sub-10 nm devices. The impact of a single dopant in the channel of a nanowire transistor was investigated assuming a ballistic/dissipative regime in Ref. 1 at low bias and only considering room temperature. In this paper, we consider the effect of the temperature (100K-400K) and the phonon scattering in a nanowire FET with a single donor close to the source at a relatively high drain bias. This work shows that the donor creates a resonant level, which makes the effect of the phonon scattering bias dependent. SIMULATIONS We are using Non-Equilibrium Green Function Formalism (NEGF) in the coupled mode space representation with 3D electrostatic. The NEGF methodology has been applied successfully to the simulation of semiconductor nano-devices and quantum cascade lasers. Its success arises from powerful recursive algorithms coupled with the non-perturbative treatment of impurities and surface/interface roughness [2-4] and the easy incorporation of dissipation
through self-energies [5,6]. The double space represent
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