A technique for positron spectroscopy of monovacancies formed by low-temperature ion implantation of silicon

A system for positron beam-based Doppler broadening spectroscopy of the formation and evolution of monovacancy defects in silicon is described. The apparatus allows in situ ion implantation at low temperatures ( 50 K) followed by positron beam assay. First measurements for 6 keV He implantation, at post-implant temperatures between 60 and 300 K are presented. Benefits and drawbacks of this system are discussed.