Evaluation of ionization yields under gallium bombardment

The Cameca NanoSIMS 50 is known to provide high resolution chemical mapping for negatively charged secondary ions (50-100 nm). Nevertheless, concerning positive secondary ions, the resolution is only in the 250-nm range. In order to obtain a better lateral resolution for positive ions, a Liquid Metal Ion Gun (LMIG, Canion 31+, Orsay-Physics, Fuveau, France) filled with gallium (Ga+) has been installed on the Cameca IMS-6F. In the case of this study, we have measured the useful yields in inorganic samples. Limitations in the secondary ion signal intensity, which is inherent to the Gallium bombardment, can be partly balanced by using oxygen flooding, as a method to enhance the ion yield. Examples of applications are presented to demonstrate that the IMS-6F equipped with a Gallium LMIG fulfills the requirements to be a complementary technique to the NanoSIMS. Copyright (C) 2010 John Wiley & Sons, Ltd.