TY - JOUR
T1 - Positron annihilation in Cr, Cu, and Au layers embedded in Al and quantum confinement of positrons in Au clusters
AU - Pikart, Philip
AU - Hugenschmidt, Christoph
AU - Horisberger, Michael
AU - Matsukawa, Yoshitaka
AU - Hatakeyama, Masahiko
AU - Toyama, Takeshi
AU - Nagai, Yasuyoshi
PY - 2011/7/11
Y1 - 2011/7/11
N2 - Defect-sensitive and element-selective measurements on ultrathin chrome, copper, and gold layers embedded in aluminium are presented using coincident Doppler broadening spectroscopy (CDBS) with a monoenergetic positron beam. The amounts of positrons implanted in the layers of different thicknesses are calculated and compared with the experimentally gained fractions of positrons annihilating in the buried layers. A high sensitivity was already reached at an Au layer of only 2 nm thickness embedded below 200 nm Al, which was attributed to the highly efficient positron trapping in the Au layer and Au clusters. An implantation and diffusion model describes this high sensitivity for positron trapping layers. A quantum-well model of the positron wave function limits the trapping to gold clusters of a radius larger than 0.23 nm. This result was confirmed experimentally and validated with complementary TEM measurements.
AB - Defect-sensitive and element-selective measurements on ultrathin chrome, copper, and gold layers embedded in aluminium are presented using coincident Doppler broadening spectroscopy (CDBS) with a monoenergetic positron beam. The amounts of positrons implanted in the layers of different thicknesses are calculated and compared with the experimentally gained fractions of positrons annihilating in the buried layers. A high sensitivity was already reached at an Au layer of only 2 nm thickness embedded below 200 nm Al, which was attributed to the highly efficient positron trapping in the Au layer and Au clusters. An implantation and diffusion model describes this high sensitivity for positron trapping layers. A quantum-well model of the positron wave function limits the trapping to gold clusters of a radius larger than 0.23 nm. This result was confirmed experimentally and validated with complementary TEM measurements.
UR - http://www.scopus.com/inward/record.url?scp=79961226411&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=79961226411&partnerID=8YFLogxK
U2 - 10.1103/PhysRevB.84.014106
DO - 10.1103/PhysRevB.84.014106
M3 - Article
AN - SCOPUS:79961226411
VL - 84
JO - Physical Review B - Condensed Matter and Materials Physics
JF - Physical Review B - Condensed Matter and Materials Physics
SN - 0163-1829
IS - 1
M1 - 014106
ER -