Formation of ncl-Si in the Amorphous Matrix a-SiOx:H Located near the Anode and on the Cathode, Using a Time-Modulated DC Plasma with the (SiH4–Ar–O2) Gas Phase (\({{{\text{C}}}_{{{{{\text{O}}}_{2}}}}}\) = 21.5 mol %)

Abstract

The formation of ncl-Si in the amorphous matrix a-SiO_x:H using a time-modulated DC plasma at an elevated oxygen content of \({{C}_{{{{{\text{O}}}_{2}}}}}\) = 21.5 mol % in a gas mixture of (SiH₄–Ar–O₂) is investigated. Plasma modulation implies the repeated (n = 180) switching on (for t_on = 5, 10, 15 s) and switching off (for t_off = 5, 10, 15 s) of the magnet coil of the DC magnetron. The effect of self-induction is used to enhance the processes of SiH₄ dissociation, the formation of Si nanoparticles, and the ionization of oxygen and ncl-Si flows towards the electrodes. The samples are located both on an electrically isolated substrate holder near the anode and on the cathode (beyond its erosion zone). These experiments show that the shape of the dependences of the photoluminescence intensity \(I_{{{\text{PL}}}}^{{ncl - {\text{Si}}}}\) on the wavelength Λ are identical for all pairs of samples on the anode and cathode. When the t_on value is small (t_on = 5 s), the difference in the sample location only slightly affects the infrared (IR) spectra. At longer times t_on (≥10 s) and a short time t_off (5 s), the amorphous matrix located on the cathode is enriched with oxygen (as compared with that near the anode). The optimal plasma-modulation parameters are found to be t_off/t_on = 5, 10, 15/10 and t_off/t_on = 5, 10/15; under these conditions, the amorphous matrix has a “perfect structure” and is transparent to radiation, and the \(I_{{{\text{PL}}}}^{{ncl - {\text{Si}}}}\) value is the largest in the range λ ≈ 0.75–0.9 μm.