An ion beam spot size monitor based on a nano-machined Si photodiode probed by means of the ion beam induced charge technique

In this work the utilization of Ion Beam Induced Charge (IBIC) technique is explored to assess resolution a 2 MeV Li + ion microbeam raster scanning micrometer-sized FIB-machined hollows in silicon photodiode. The analysis maps crossing FIB machined structures evidenced drop charge collection efficiency across perimeter combined with significant recovery signal amplitude at center microstructures, thus forming feature which can be exploited estimate probing beam. results were interpreted according numerical simulations based on Shockley-Ramo-Gunn as originating from FIB-induced surface space density. These offered additional information respect what achievable by confocal photocurrent microscopy same device, due significantly shorter focal depth latter This study suggests viability an effective method evaluate microbeams processes and experiments, could beneficial emerging fields (deterministic implantation, micro-radiobiology, lithography) demanding beam spot sizes below micrometer scale.