The obtention of luminescent SiO_xC_y:H thin films deposited by the HW-CVD technique is reported here. We study the effect of different monomethyl-silane (MMS) flow rates on the films properties. An increase in the emission bandwidth and a red-shift was observed when the MMS flow increased. The luminescence was related to optical transitions in band tail states and with less contribution from quantum confinement effects. After, the films were annealed at 750 °C in nitrogen. The annealed film deposited at the highest MMS flow showed an emission spectrum like the as-deposited film, suggesting the same emission mechanisms. By contrast, the annealed film deposited at the lowest MMS flow showed two emission bands. These bands are due to the activation of radiative defects related to oxygen-deficient centers. MOS-like structures were fabricated as electroluminescent devices using the annealed films. Only the structure of the film with the highest carbon content showed light emission in a broad band in the visible spectrum region in forward bias, with a maximum centered close to 850 nm. The light emission mechanism was related to electron thermalization in the band tail states and a direct hole injection into deep states. The trap-assisted tunneling, Poole–Frenkel emissions and Fowler–Nordheim tunneling were proposed as the charge transport mechanism.

This paper presents the structural, optical and electrical characterization of ZnO thin films obtained by ultrasonic spray pyrolysis (USP). Based on these characterizations, the deposition conditions that provide films with higher crystallinity and greater absorption were determined. The resistivity of the films was reduced by annealing in nitrogen environment and was measured with a 4-point probe. The annealed films were characterized by AFM, SEM and XPS. Two photoconductive detectors were fabricated, with high and low resistivity films, and the responsivity was obtained for both. The two detectors showed a high UV response, but the photodetector developed from the annealed film demonstrated a maximum responsivity of 3000 A/W at 369 nm with a 2 V bias voltage. This result is higher than results obtained with low-cost techniques such as sol-gel, pneumatic spray pyrolysis, and even some results reported by sputtering.