Luminescence of polymorphous silicon carbon alloys

Polymorphous silicon carbon alloys (pm-Si_1-xC_x:H) have been prepared from the decomposition of SiH₄-CH ₄-H₂ mixtures at 200 °C in a standard capacitively coupled RF glow discharge reactor at high pressure, under conditions where silicon clusters, nanocrystals and their agglomerates are produced in the plasma and contribute to the deposition. Visible photoluminescence (PL) was observed at room temperature in these materials in the spectral region from red to orange. The PL intensity and peak position show a strong dependence on the deposition pressure. Moreover, electroluminescent (EL) diodes with p-i-n structure were realized using the optimized materials as the i-layer. EL spectra, comparable to the PL ones, were obtained by applying a DC voltage above 8 V. EL is stable for several hours of continuous operation which makes these devices interesting for applications.