1. Ryan Weed Centre for Antimatter- Matter Studies VACANCY CLUSTERS IN SELF-ION IMPLANTED GERMANIUM STUDIED WITH PALS

2. BEAMLINE OVERVIEW

3. Transport coils Trap Source Sample station detector

4. PALS ANALYSIS

6. MOTIVATION  Germanium is a good candidate to replace Silicon in CMOS devices  3-4 times higher mobility (determines device speed)

7. 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

8. ION IMPLANTATION  800 keV Ge + implantation  Fluence between 3x10 12 and 3x10 14 cm -2  Vacancy and interstitials damage distribution simulated in SRIM

9. RBS RESULTS

10. 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

11. PALS RESULTS  Vacancy clusters formed in both samples  Cluster size expected in magic numbers (N=6,10,14)  Clusters dissolve at 500 C in both samples

12. 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

13. 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