Effect of surface treatment on the electron field emission property of nano-diamond films

Nano-diamond films having grain size around 20 nm were deposited by bias enhanced growth (BEG) method. Different surface treatments were carried out to increase their field emission properties and their effects are clearly noticed. Surface morphology of different surface treated nano-diamond films was examined. There was no significant change in the curve of Raman spectra of different surface treated samples. Raman spectra were typically of similar nature to nano-diamond film. Field emission results were more interesting. Biased in hydrogen plasma treated nano-diamond film has shown best electron emission behavior and low turn-on-field (E0). The turn-on-field of bias-treated nano-diamond film was 19.5 V/μm. The decrease of turn-on-field (∼6 V/μm) of biased treated nano-diamond film from as-grown BEG film was attributed to the formation of thin sp2 layer and more defects on the surface of film by hydrogen ion bombardment. Moreover, hydrogen-plasma treated nano-diamond film was also found to be good for electron emission but there was no improvement in electron emission as in the case of air plasma treated nano-diamond films.