Structural and optical properties analysis of Al nanoparticle-assisted SiO_x thin film for photodetector application

This study investigated the effect of aluminium (Al) nanoparticle (NP) assisted on SiO_x thin film for possible enhancement in photodetection using catalyst free e-beam evaporation with the glancing angle deposition technique. The X-ray diffraction spectrum confirms the presence of Al-NP, which is further supported by energy dispersive X-ray analysis. The top view field emission scanning electron microscope image of the p-Si/SiO_x/Al-NP/SiO_x/Al-NP sample reveals the successful deposition of a porous SiO_x film coated with Al-NP. The optical absorption spectra of the samples with Al-NP show enhanced absorption in the UV as well as in the visible region compared to the samples without Al-NP, which may be due to the surface plasmon resonance effect of Al-NP. The measured photocurrent densities for the annealed p-Si/SiO_x/Ag and p-Si/SiO_x/Al-NP/SiO_x/Al-NP/Ag devices were found to be about -2.02 x 10^-3 and -5.53 x 10^-3 A cm^-2 at -8 V, respectively. Moreover, the annealed p-Si/SiO_x/Al-NP/SiO_x/Al-NP/Ag based device shows improved rise time (∼106 ms) and fall time (∼108 ms) as compared to the rise time (∼135 ms) and fall time (∼192 ms) of p-Si/SiO_x/Ag based device. These results indicate that the addition of Al metal NP assisted on SiO_x thin film has a good impact on optical and electrical properties, which makes the proposed fabrication technique a promising one for photo detector and other optoelectronic applications. (author)