Charge-buildup effect during ion-beam irradiation of an insulator and its suppression by deposition of a thin metal film

During ion-beam irradiation, an electric potential is induced on the surface of an insulator sample owing to electric charge buildup. Because this uncontrollable built-up voltage causes energy fluctuations of the incoming ions and the exiting charged particles, the uncertainty in ion-beam analyses, such as Rutherford backscattering spectrometry and elastic recoil detection increases. In order to suppress the charge buildup effect, we deposited a thin gold film on the sample surface. Using a He beam, we measured the built-up voltage at the insulator surface as a function of the Au film thickness. We determined the minimum thickness necessary to suppress such an effect for several insulators samples.