Structural and electrical transport properties of excimer (Arf)-laser-crystallized silicon carbide

The structural and electrical properties of undoped and doped microcrystalline silicon carbide ((μc-SiC) thin films prepared by excimer (ArF) laser crystallization of plasma-enhanced chemical vapour deposited hydrogenated amorphous silicon carbide (a-SiC: H) have been analysed. Using transmission electron microscopy this material is shown to possess partial β-SiC structure. Bonding configurations have also been characterized by infrared spectroscopy. It is shown that a-SiC: H films having a carbon content as large as 30 at.% can be crystallized by this novel method. After crystallization, all films show greater than six orders of magnitude increase in dark conductivity σdc. The temperature dependences of σdcfor undoped, n- and p-type μc-SiC exhibit different characteristic shapes. For all samples, it is shown that the increase in σdcis not predominantly due to the activation of dopant atoms. Instead, the change is associated with the formation of a microcrystalline structure. However, dopant sites, but not carbon content (up to 30 at.%), play an important role in electrical transport in μc-SiC.