GAAS JUNCTIONLESS FINFET FOR HIGH PERFORMANCE ANALOG APPLICATION IN SUB-25 NM REGIME

Abstract

When a conventional MOSFET is decreased in size many short channel effects come into play. These short channel effects include Drain Induced Barrier Lowering, Tunneling into and through gate oxide, Threshold Voltage Roll-Off, Drain Punch Through. To reduce these effects a new device has been proposed named GaAs Junctionless FinFET using high-ᴋ dielectric. Junctionless device can help reduce these effects but it suffers from lower switching ratio. To maintain the switching ratio to an optimal level new techniques have been introduced like use of metal gate and high-ᴋ material. In this Work GaAs Junctionless FinFET is designed in Sub-25 nm regime. Firstly, GaAs Junctionless SOI FinFET is designed using high-k spacer. This is compared with two other fin material (Si and Ge). Proposed device is found to provide a higher switching ratio. Charge density in the device is compared for three different fin materials. Further SOI is replaced with HfO2 which leads to increase in switching ratio. Change in Fermi level is noted for the device, which is compared with JL FinFET. When device is off, difference between Fermi level and conduction band is more in the proposed device which is a reason for lower off current. Further, temperature analysis is done on the device. At high temperature on current shows 18% increase when compared to JL device. When device is in on state current is depended on mobility of the device and at off state current flow is found to be depended on charge density. As mobility is decreased with increase in temperature, so on state current decreases and due to increase in charge density with temperature, device is found to have an increase in leakage current. As device shows higher switching ratio even at high temperature so device can be used as a good alternative for conventional device. Further, a grove can be introduced in place of spacer; biomolecules can settle in that grove. Change in dielectric of the grove region can lead to change in current of the device. This device can be used as a protein sensor.