Fabrication of Visible-Enhanced BxC/SiO2/Si Photodetector by One-Step Laser Ablation

The synthesis of advanced and hard nanoparticles has attracted considerable interest because of their industrial and technological uses. The most crucial factor in selecting the best preparation method is the ability to control the morphology and size of the nanoparticles. Herein, we report for the first time the effect of laser fluence on the properties of boron carbide (BxC) nanoparticles (NPs) synthesized via pulsed laser ablation in ethanol. The X-ray diffraction results revealed that the synthesized BxC nanoparticles are polycrystalline with a rhombohedral phase. As laser fluence increased, the direct optical energy gap of BxC decreased from 2.16 to 1.94 eV. Fluorescence measurement shows a strong single emission peak centered at 580, 610, and 622 nm is observed for samples prepared at 6.3, 12.7, and 19.1 J/cm2/pulse, respectively. Raman spectra of BxC nanoparticles show the existence of seven vibration modes located at 270, 320, 480, 533, 722, 820, and 1080 cm-1 and their intensity depends on the laser fluence. The field emission scanning electron microscope (FESEM) investigation displays the production of spherical nanoparticles of different sizes, and particle agglomeration was noticed at 19.1 J/cm2/pulse. The fabrication and characterization of BxC NPs/SiO2/Si heterojunction photodetectors is demonstrated. The dark I-V characteristics of the BxC NPs/SiO2/Si heterojunction confirmed the best junction characteristics were found for the heterojunction fabricated at 19.1 J/cm2/pulse. The photosensitivity studies show that the maximum detector's responsivity was 0.78 A/W at 450 nm. The highest values of specific detectivity and quantum efficiency were 2.61 × 1012 Jones and 2.1 at 50 nm, respectively. The ON/OFF measurement was performed to investigate the response/recovery time and switch behavior of the photodetectors.