Experimental and theoretical approaches of electron emission from hydrophobic rGO modified silicon nanowires

Grass like tapered silicon nanowires are synthesized by metal assisted chemical etching process under 60 C temperature for 40 (SiNW40), 60 (SiNW60) and 80 min (SiNW80) to investigate the optimum time of etching for the SiNWs to act as an efficient field emitter. It is observed that 60 min of HF etching are optimum for silicon nanowires for its low turn-on field but SiNW80 requires higher turn-on field than SiNW60 though the current density is extremely high after reaching the turn-on electric field. This disadvantage is attributed to the tip bundling effect of SiNW80. In order to obtain low turn-on field along with high current density, SiNW80 is wrapped with rGO for the first time and it shows the lowest turn-on field of 0.12 V/mu m with the highest current density. Surface roughness properties related to field emission are analyzed by wettability study. Additionally, ANSYS simulation conducted for the theoretical validation of field emission properties has added another novelty of work. There is reduction of work function from SiNW80 to rGO-SiNW80 as obtained from the computational analysis. Morphological variation, surface edges, surface roughness related to water contact angle, moderate work function and energy band bending cause such enhancement field emission properties.