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

Abstract

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 [sgrave]_dc. The temperature dependences of [sgrave]_dc for undoped, n- and p-type μc-SiC exhibit different characteristic shapes. For all samples, it is shown that the increase in [sgrave]_dc is 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.