Feb 6 – 8, 2006
CERN
Europe/Zurich timezone

Lattice location of Ag in SrTiO3 and new developments in position-sensitive detectors for Emission Channeling

Feb 7, 2006, 5:15 PM
20m
Council Chamber, 503/1-001 (CERN)

Council Chamber, 503/1-001

CERN

CH-1211 Geneva 23

Speaker

A.C. Marques (Centro de Física Nuclear da Universidade de Lisboa, Portugal)

Description

Strontium-titanate is a perovskite ceramic material, which is of interest, e.g., for future devices based on metal-oxide Si heterostructures such as high-k field effect transistors. The electrical, optical and magnetic properties of SrTiO3 can be modified by the incorporation of dopants. For instance, transition metal doped SrTiO3 has been considered as a candidate for a room-temperature ferromagnetic semiconductor [1]. Ion implantation might thus represent an attractive approach for doping, especially in cases where the solubility of dopants is limited and they cannot be introduced during growth. However, very little is known about the fundamental question whether implants are incorporated on proper lattice sites in SrTiO3 (substitutional Sr, substitutional Ti and substitutional O sites, regular interstitial sites or randomly dispersed). This can be studied with the emission channelling technique, which unambiguously identifies and quantifies the impurity lattice site location. Results for implanted 111Ag in SrTiO3 perovskite are reported to illustrate the EC technique capabilities. Electron channeling patterns were measured around several crystalline directions following in-situ-vacuum annealing up to 900ºC. It is shown that in the as-implanted state, Ag occupies several lattice sites and upon annealing, most of Ag goes to near-substitutional Sr sites [2], while for instance Fe is to a large extent incorporated on Ti substitutional sites. In addition, a short description of a new data readout technology for electron Si pad detectors with a strong impact on the applications of the EC technique will be presented. The new technology improves the detection efficiency of very low energy conversion electrons below 40keV, and at the same time, allows very high readout count rates up to tens of kHz. These facts will broaden the range of available elements for EC studies, in particular, by using short-lived isotopes, already next year. Perspectives about the near future of the EC technique at ISOLDE-CERN will be given. [1] S.J. Pearton, W.H. Heo, M. Ivill, D.P. Norton, and T. Steiner, Semicond. Sci. Tech. 19 (2004) R59-74. [2] A.C. Marques, U. Wahl, J.G. Correia, E. Rita and J.C. Soares, “Lattice location and perturbed angular correlation studies of implanted Ag in SrTiO3”, accepted by Nucl. Instr. And Meth B (2005).

Primary author

A.C. Marques (Centro de Física Nuclear da Universidade de Lisboa, Portugal)

Co-authors

E. Rita (Centro de Física Nuclear da Universidade de Lisboa, Portugal) J.C. Soares (Centro de Física Nuclear da Universidade de Lisboa, Portugal) J.G. Correia (Instituto Tecnológico e Nuclear, Sacavém, Portugal) U. Wahl (Instituto Tecnológico e Nuclear, Sacavém, Portugal)

Presentation materials