Introducing Ohmic Contacts into Silicon Carbide Technology

Abstract

The promising mechanical and electronic properties of silicon carbide (SiC) are stimulating extensive investigations focused on the applications of its semiconducting and excellent structure properties. As a matter of fact, the interest toward SiC is twofold. On one hand, it is a high-strength composite and high-temperature structural ceramic, demonstrating the ability to function at high-power and caustic circumstances. On the other hand, it is an attractive semiconductor, which has excellent inherent characteristics such as a wide band gap (3.3 eV), high breakdown field (3 × 106 V/cm), more than double the high carrier mobility and electron saturation drift velocity (2.7 × 107 cm/s) of silicon (Morkoc et al., 1994). These intrinsic electronic properties together with the high thermal conductivity (5 W/cm K) and stability make it the most likely of all wide-band-gap semiconductors to succeed the current Si and GaAs as next-generation electronic devices, especially for high-temperature and highfrequency applications. Successful fabrication of SiC-based semiconductor devices includes Schottky barrier diodes, p-i-n diodes, metal-oxide-semiconductor field effect transistors, insulated gate bipolar transistors and so forth. Moreover, current significant improvements in its epitaxial and bulk crystal growth have paved the way for fabricating its electronic devices, which arouses further interest in developing device processing techniques so as to take full advantage of its superior inherent properties. One of the most critical issues currently limiting its device processing and hence its widespread application is the manufacturing of reliable and low-resistance Ohmic contacts ( 1020 cm-3) were formed, the key problem of this method is the easy formation of lattice defects or amorphization during the ion implantation. These defects are unfortunately very stable and need to be recovered via post-annealing at an extremely high temperature (~ 2000 K), thereby complicating mass production of SiC devices.