Amorphous-CNx:H films were formed using supermagnetron plasma CVD. In this experiment, the rf powers supplied to the upper electrode (UPRF) and lower electrode (LORF) were controlled to 10 and 5-800 W, respectively. The optical band gap of the a-CNx:H film was found to decrease largely from 2.6 to 0.22 eV with the increase of LORF from 5 to 800 W. The hardness increased from 5.9 to 27.5 GPa with the increase of LORF from 5 to 200 W, and then it decreased gradually to 10.7 GPa with the further increase of LORF to 800 W. FT-IR absorption spectrum showed strong C-H stretching mode vibration at low LORF, i.e., films formed at low LORF included many hydrogens bonded to carbons. The photoluminescence (PL) was measured, and it was found that the wide optical-band-gap a-CNx:H film formed at UPRF/LORF of 10/10 W showed broad white PL. (c) 2004 Elsevier B.V. All rights reserved.