Modeling and comparative analysis of Si-MOSFET and GaAs FETs for high speed devices

Abstract

For the last few decades, silicon has been the promising device for realizing digital and analog circuits in integrated circuits. It is widely used for implementing a MOS-FET device. In the present work, Si-MOSFET characterization is examined. This has been performed using SPICE and ADS tools. Characterization of silicon device using ADS has been incor-porated vary less. This has been innovatively taken in the present work. The results obtained from ADS are compared with the SPICE tool. It is observed that the results of ADS and SPICE are in good agreement with each-other. The conventional silicon device possesses high delay and power dissipation, generally at high frequencies, various signal integrity is-sues come up significantly. To manipulate this, Researchers� have investigated compound semiconductor material like GaAs which has many distinct advantages such as higher mo-bility, high resistivity and low saturation velocity over silicon. It can be used in integrated circuits to overcome the limitations of Silicon.In this project, several analyses have been performed to identify the performance of sili-con and GaAs based devices. DC and Transient analysis have been performed. It is seen that Gallium Arsenide MESFET gives better performance over silicon because of the high electron mobility. In GaAs, it is observed that the drain current is comparatively higher than that of silicon. Henceforth, GaAs MESFET can be used in high speed devices like digital ON-OFF switching circuits. However, there is one limitation of Gallium Arsenide is that it possesses poor hole mobility than Silicon. Hence realization is only NMOS is possible.In the present work, a digital circuit like resistive load inverter, NAND and NOR gates are implemented using a prominent GaAs based device. This is then compared with a sili-con based device. It is seen that GaAs gives good performance than its counterpart Si based simulations. GaAs is hence very effective for high speed applications and operated at high frequencies.