Hydrogenated amorphous and crystalline SiC thin films grown by RF-PECVD and thermal MOCVD; comparative study of structural and optical properties

Abstract

Thin films of hydrogenated amorphous silicon carbide (a-SiC:H) and crystalline silicon carbide (c-SiC) with different compositions were deposited on Si(1 0 0) substrates by both RF plasma enhanced chemical vapor deposition and thermal metal organic chemical vapor deposition methods using a SiH4 + CH4 gas mixture and a single molecular precursor of diethylmethylsilane, respectively. In this experiment, we mainly investigated the dependence of structural and optical properties of a-SiC:H and c-SiC thin films on the deposition parameters such as deposition temperature, pressure, RF power and annealing temperature. From this comparative study on structural and compositional differences of the a-SiC:H and c-SiC thin films, we realized that there are much different hydrogen contents and crystallinity in the films depending on the deposition temperature and annealing temperature. With increasing these parameters, moreover, the hydrogen contents and crystallinity are drastically changed to be less hydrogen and better crystalline films starting from amorphous, polycrystalline and single crystalline, sequentially. In addition, their optical properties are also strongly changed, for example, the refractive index and optical band gap are increased with increasing deposition temperature, pressure, RF power and annealing temperature. And the structural and optical properties of c-SiC thin film were analyzed with X-ray diffraction, scanning electron microscope, and infrared absorption techniques. (C) 2003 Elsevier Science B.V. All rights reserved.