Deposition of luminescent a-SiNx:H Films with SiH4–N2 gas mixture by VHF–PECVD using novel impedance matching method

Hydrogenated amorphous silicon nitride (a-SiN x :H) films are produced from a SiH4–N2 gas mixture by plasma enhanced chemical vapor deposition(PECVD) system with a newly developed impedance matchingmethod at frequencies 13.6–150 MHz. An increase in the rf power from 35 to 350 mW/cm2 at the highest frequency of 150 MHz increases the optical bandgap (E opt) from 2.0 to 4.5 eV. Optical emission spectroscopy (OES) of the SiH4–N2 plasma shows that the emission intensityof SiH* (414 nm) is almost proportional to deposition rate. Films of a-SiN x :H deposited at 150 MHz and 210 mW/cm2 has an optical bandgap of E opt ≈ 4.1 eV and emits visible photoluminescence (PL) at room temperature (RT).