Experimental comparison between Nb2O5- and TiO2-based photoconductive and photogating GFET UV detector

Abstract In the present study, by adding graphene to a photoconductive photodetector with a niobium pentoxide (Nb2O5) absorber layer and exploiting the photogating effect, the responsivity of the photodetector is significantly improved. In this photodetector, the Nb2O5 layer detects the light, and the graphene improves the responsivity based on the photogating effect. The photocurrent and the percentage ratio of the photocurrent to dark current of the Nb2O5 photogating photodetector are compared with those of the corresponding photoconductive photodetector. Also, the Nb2O5 photoconductive and photogating photodetectors are compared with titanium dioxide (TiO2) photoconductive and photogating photodetectors in terms of responsivity at different applied (drain-source) voltages and gate voltages. The results show that the Nb2O5 photodetectors have better figures of merit (FOMs) in comparison with the TiO2 ones

Laser-Induced Breakdown Spectroscopy Via the Spatially Resolved Technique Using Non-Gated Detector

We present a simple setup for laser-induced breakdown spectroscopy using the spatially resolved technique (SRLIBS). We show that, without any need for time-gated ICCD and pulse generator, the signal-to-background ratio is enhanced. We develop a homemade spectrograph with a movable slit located at its entrance to detect different parts of the plasma emission. For optimizing the position of the slit, we use the shadowgraphy technique to study the plasma expansion. In this low cost setup, with nanosecond laser pulses, we perform SRLIBS experiments on the plasma induced in air and iron. Our results show that the signal-to-background ratio for iron and air is enhanced up to 15 and 8 times, respectively