Overview

Silicon carbide (SiC) offers significant advantages for microwave high power devises due to its unique electrical and thermal properties. This review presents a summary of the current position in the development of silicon carbide diodes operating at microwave frequencies: varactors, Schottky barrier mixer diodes, p-i-n and IMPATT diodes. Simplified theory of device operation is given for each kind of microwave diodes to derive the figures of merit, to estimate the potential silicon carbide performance for fabrication of these diodes and to compare SiC with conventional semiconductors. These analyses are followed by description of diode design, fabrication and measured characteristics.

Keywords: silicon carbide; microwave; Schottky barrier diode; mixer; varactor; detector; p-i-n diode; IMPATT diode

1 Introduction

Silicon carbide (SiC) is a very attractive material for high power, high voltage and high temperature applications due to its superior electrical and thermal properties. ^[1] Silicon carbide occurs in more than 170 different crystal structures (called polytypes) with each crystal structure having its own unique electrical and optical properties. The electrical properties of the commercially available 4H- and 6H-SiC polytypes are compared to the properties of silicon and GaAs in Table 1. The only disadvantage of silicon carbide evident from this data is the low electron mobility. However, very high breakdown field, wide band gap energy, high electron saturation velocity, and high thermal conductivity may lead to...