Influence of high energy ion irradiation on the field emission characteristics of CVD diamond films

The field emission characteristics of ion-irradiated CVD diamond thin film deposited on silicon substrate has been studied. The diamond thin films, synthesized by hot filament chemical vapor deposition (HFCVD) method, were irradiated by high energy (100 MeV) silver ion (107Ag+ with charge state 9) in the fluence range of 3 × 1011–1 × 1013 ions/cm2. The CVD diamond films were characterized by Raman spectroscopy. The Raman spectra of irradiated samples clearly reveal structural damage due to ion irradiation, which is observed to be fluence dependent. However complete graphitization is not observed. The field emission current–voltage (I–V) characteristics were recorded in ‘diode’ configuration at base pressure ∼1 × 10−8 mbar. Upon ion irradiation the field emission current is observed to increase with the reduction in the threshold voltage, required to draw 1 μA current. The results indicate that ion irradiation leads to better emission characteristics and the structural damage caused by ion irradiation plays a significant role in emission behavior of CVD diamond films.