Prospects of a β-SiC based IMPATT oscillator for application in THz communication and growth of a β-SiC p—n junction on a Ge modified Si (100) substrate to realize THz IMPATTs

Abstract

The prospects of a p+nn+ cubic silicon carbide (3C-SiC/β-SiC) based IMPATT diode as a potential solid-state terahertz source is studied for the first time through a modified generalized simulation scheme. The simulation predicts that the device is capable of generating an RF power output of 63.0 W at 0.33 THz with an efficiency of 13%. The effects of parasitic series resistance on the device performance and exploitable RF power level are further simulated. The studies clearly establish the potential of 3C-SiC as a base semiconductor material for a high-power THz IMPATT device. Based on the simulation results, an attempt has been made to fabricate β-SiC based IMPATT devices in the THz region. Single crystalline, epitaxial 3C-SiC films are deposited on silicon (Si) (100) substrates by rapid thermal chemical vapour deposition (RTPCVD) at a temperature as low as 800 °C using a single precursor methylsilane, which contains Si and C atoms in the same molecule. No initial surface carbonization step is required in this method. A p—n junction with an n-type doping concentration of 4 × 1024 m−3 (which is similar to the simulated design data) has been grown successfully and the characterization of the grown 3C-SiC film is reported in this paper. It is found that the inclusion of Ge improves the crystal quality and reduces the surface roughness.