Amorphous, hydrogenated, silicon carbide (a-SiC:H) films are deposited in the remote hydrogen microwave plasma (RP-CVD) process using diethylsilane as a single-source precursor. The effect of substrate temperature (TS) on the kinetics of RP-CVD, chemical composition, structure, surface morphology, and properties (density, refractive index, and extinction coefficient) of the resulting a-SiC:H films is investigated. The TS dependence of film growth rate implies that RP-CVD is an adsorption-controlled process. The increase of TS from 30 °C to 350 °C causes the elimination of organic moieties from the film and the formation of a SiC network structure. The relationships between the content of SiC bonds, represented by the relative integrated intensity of the SiC IR band, and the film properties are determined. The number of SiC bonds is found to be a key parameter in the control of the examined film properties. The films deposited at TS = 350 °C appear to be very dense materials exhibiting small surface roughness and high refractive index. The results of the present study are compared with those reported for a-SiC:H films produced by RP-CVD from a triethylsilane precursor.