We have investigated the gas pressure dependence of electron cyclotron resonance (ECR) plasma‐enhanced chemical vapor deposition (PECVD) and preparedn‐type &mgr;c‐SiC:H with wide optical band gap (2.1–2.5 eV) and high dark conductivity (10−3– 1 S/cm). It has been suggested from plasma diagnoses of the ECR plasma that at low gas pressure a strong etching effect of hydrogen radicals and/or ions dominates the film growth process and the hydrogen ions impinging on the growing surface make the formation of &mgr;c‐SiC:H difficult, and that at high gas pressure, for the formation of &mgr;c‐SiC:H, there are nonemissive radicals contributing to the surface coverage or a nucleus formation mechanism which has not been taken into consideration in conventional rf‐PECVD.