Ryan Weed

Centre for Antimatter-Matter Studies

VACANCY CLUSTERS IN SELF-ION IMPLANTED GERMANIUM STUDIED

WITH PALS

BEAMLINE OVERVIEW

BEAMLINE OVERVIEW

Transport coils TrapSource

Sample station

detector

PALS ANALYSIS

PALS ANALYSIS

MOTIVATION

Germanium is a good candidate to replace Silicon in CMOS devices

3-4 times higher mobility (determines device speed)

MOTIVATION

Implantation induced defects eff ect electrical activation

Dopant-defect relationship not well understood in Ge

Diff usion mechanisms dissimilar to Si

Positrons well suited to study evolution of vacancy type defects under thermal treatment

ION IMPLANTATION

800 keV Ge+ implantation

Fluence between 3x1012 and 3x1014 cm -2

Vacancy and interstitials damage distribution simulated in SRIM

RBS RESULTS

RBS RESULTS

As-implanted Annealed

High fluence sample ‘amorphized’ by ion implantation

No damage detected in low fluence sampleSPEG of amorphous region complete at 400 C anneal

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

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 diff er

Mobility diff erences or SPEG eff ect

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