Research On InN/SiGe/Si Tunneling Field Effect Transistor With Low Off-state Current

Under the guidance of Moore's Law, the integration of microprocessors continues to improve, driving the development of logic switching devices. In the logic switching device, the tunneling field effect transistor (TFET) breaks through the theoretical limit of the subthreshold swing of the metal-oxide-semiconductor field-effect transistor(MOSFET), which effectively turns on and off the device and becomes hotspots in the field of research. In the working principle, the TFET device is based on quantum mechanics, and utilizes the carrier band-to-band tunneling to realize the work of the device, which is different from the working mode of the MOSFET device in order to avoid all the short channel effect of the small size MOSFET device. As the chip integration continues to increase, the electrical requirements for TFET devices are increasing, requiring higher open-state currents and lower off-state currents. In order to improve the electrical performance of the TFET device, some researchers designed the TFET device with a narrow band gap, shortening the band gap of carrier tunneling and significantly increasing the on-state current of the device. However, this type of TFET device would have so large off-state current, which causes that the device could not be effectively shut down, that have an influence on the normal operation of the circuit. In this paper, we propose a method to construct a TFET device by using a silicon-based material and a narrow bandgap InN material, increasing the electric field at the tunnel junction to enhance the open-state current of the device with the help of polarization effect of InN; suppressing the drift and diffusion of carriers during off-state in order to reduces the off-state current of the device by using InN/Si heterojunction potential barrier. The main research work is:Firstly, considering the wide bandgap width at the tunneling junction of the silicon-based TFET device, the germanium-silicon material is introduced into the source region to adjust the bandgap width at the tunneling and enhance the carrier current and keep the low- State current.Secondly, changing the film of the dielectric constant on the surface of the silicon-based TFET device, the variation of the tunneling electric field is observed when the device is turned on. We will analyze influence of dielectric constant on electric field and current of TFET Device.Subsequently, an InN material is introduced into the silicon-based TFET device.Since InN belongs to Group III-V nitride, it has a small band gap, which facilitates carrier tunneling. In addition, InN material has a piezoelectric polarization effect which induces polarized electric field and polarized charge. InN material is introduced into the silicon-based TFET device to form the InN/Si heterojunction, and the on-state current is enhanced by the polarization electric field of InN, and the off-state current of the device is suppressed by the potential barrier of heterojunction. Therefore, InN/Si heterojunction TFET with low off-state current is proposed.Finally, according to the above design methods of TFET devices, the device structure is designed by using the Sentaurus simulation tool in TCAD, and the electrical simulation under specific physical model is implemented for analysis of device structure,on-state current and off-state current. The proposed InN/Si heterojunction TFET device with low off-state current has an on-state current of 0.1mA/?m and a off-state current of 0.1pA/?m with a switching ratio of 109.