Synthesis of C:Se nanoparticles via laser ablated with magnetic field on porous silicon for gas sensor applications

The presented study synthesized C:Se NPs via a combination of the laser along with magnetic field at various laser pulse energies 200, 600 and 1000mJ with 100 shots, have been deposited on the porous silicon (PS) through the use of drop-casting method. The pattern of the X-ray diffraction (XRD) had indicated the nanocrystaline of specimens. In Atomic force microscopy (AFM), which shows agglomeration of C:Se NPs increased, the distribution of the granularity showed that the distribution of part was almost Gaussian, also the transmission electron microscope (TEM) indicated that the synthesized C:Se particles have an average particle size of 35 nm. Bright-field TEM images show complementary contrast, confirming the formation of core/shell structures. The optical measurements in wavelength range ultraviolet-visible near infrared (UV-vis-NIR) as well as a transition of indirect type with 4 eV band gap is specified. Also, the electrical characteristics like barrier height (phi B), ideal factor (n) for Al/C:Se NPs/PS/Si/Al heterojunction were concluded with measurements of current-voltage (I-V). Lastly, the operation temperature variations associated with NO2 and NH3 gas sensors are subjected to fabrication from the prepared samples on response time, sensor sensitivity and recover time was examined. The maximum sensitivity of C:Se/PS at 1000 mJ gas sensor to 60 ppm of NO2 about 202.5% at around 100 degrees C, also the maximum sensitivity of C:Se/PS at 1000mJgas sensor to 200 ppm of NH3 can reach 17.9%, and the optimum sensing temperature of C: Se/PS sensor is at around 150 degrees C.