Design and simulation of Gallium Arsenide based Schottky diodes for RF applications

Abstract

Today, being the dawn of a new RF technology wave, the requirement of making semiconductor device which have greater speed in performance, which is realized either as a higher maximum frequency of operation or higher logic switching speeds. Gallium Arsenide (GaAs) based Schottky Diodes have superior RF performance with a low forward voltage drop and a very fast switching action compared silicon based diodes due to its high speed operation. Perhaps the primary benefit of GaAs comes from its electron-dynamic properties. In equivalently doped n-type GaAs and silicon, the effective mass of the electric charge carriers in GaAs is far less than that in silicon. This means that the electrons in GaAs are accelerated to higher velocities in less time. In this project, the Synopsys Taurus Workbench of MEDICI is used to simulate the GaAs based Schottky Diode to generate the device structure and model the device electrical characteristics. The objective of this project is to design GaAs-based Schottky Diodes for operation of cut-off frequency (Ft) excess 10G Hz for RF application. An initiall Schottky Diode device structure was based on the model from Telecom Malaysia Research and Development Sdn. Bhd was generated and then the electrical characteristics were extracted to obtain the cut-off frequency (Ft). The next step is to redesign a Schottky Diode which have operating cut-off frequency (Ft) excess 10G Hz by study the effect on cut-off frequency (Ft.) by varying GaAs layer doping concentration, layer thickness, device length, comparison of nitride and oxide passivation layer and lastly varying the metal work function used in metal-semiconductor junction. From all the experiment method tested as mentioned above, finally a Schottky Diode which has cut-off frequency of 10.13027G Hz was able to be designed.