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Vacancy clusters in self-ion implanted Germanium studied with PALS . Ryan Weed Centre for Antimatter-Matter Studies. Beamline overview. Beamline overview. detector. Source. Sample station. Transport coils. Trap. Pals analysis. PALS analysis. Motivation.
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Vacancy clusters in self-ion implanted Germanium studied with PALS Ryan Weed Centre for Antimatter-Matter Studies
Beamline overview detector Source Sample station Transport coils Trap
Motivation • Germanium is a good candidate to replace Silicon in CMOS devices • 3-4 times higher mobility (determines device speed)
Motivation • Implantation induced defects effect electrical activation • Dopant-defect relationship not well understood in Ge • Diffusion mechanisms dissimilar to Si • Positrons well suited to study evolution of vacancy type defects under thermal treatment
Ion implantation • 800 keVGe+ implantation • Fluence between 3x1012 and 3x1014 cm-2 • Vacancy and interstitials damage distribution simulated in SRIM
RBS results As-implanted Annealed • High fluence sample ‘amorphized’ by ion implantation • No damage detected in low fluence sample • SPEG of amorphous region complete at 400 C anneal
PALS results • Vacancy clusters formed in both samples • Cluster size expected in magicnumbers (N=6,10,14) • Clusters dissolve at 500 C in both samples
Variable energy PAls • 2,10,18keV positron energies performed on 400 C annealed samples • Similar lifetime distribution for amorphous and sub-amorphous implants • Intensity distributions differ • Mobility differences or SPEG effect
Thanks CAMS – James Sullivan, Steve Buckman, Michael Went, Jason Roberts EME – Simon Ruffell Technical Staff - Steve Battison, Ross Tranter, Colin Dedman, Graeme Cornish PPC10 organizers for help in financing my attendance