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Characterization of materials for semiconductor devices by means of positron annihilation

Vacancy-type defects in metals, insulators, and semiconductors

A positron is an antiparticle of electron. It can be obtained by radio isotopes and pair production from high energy photons. Positrons can be used to a non-destructive probe for investigating defects in materials. Because of its high sensitivity for vacancy-type defects, this technique has been used for studies of materials for semiconductor devices.

When a positron is implanted into solids, it annihilates with an electron and emits two γ-quanta. The energy distribution of the γ-rays is broadened by the momentum component of the annihilating electron-positron pair. A freely diffusing positron may be localized in a vacancy because of Coulomb repulsion from charged ion cores. Because the momentum distribution of the electrons in the defects differs from that of electrons in the bulk material, these defects can be detected by measuring the energy distribution of the annihilation radiation. Because the electron density in vacancies is lower than that in the bulk, the positron lifetime increases in vacancies. Thus, measurements of positron lifetime spectra are also used to detect the defects. In this seminar, applications of positron annihilation to studies of electroplated metals, low dielectric insulators, and wide gap semiconductors will be presented.

Seminar: Neutronen in Forschung und Industrie

Datum09.07.2018
Uhrzeit14:30 - 15:30 Uhr
OrtGarching
RaumPhysics Department TUM, HS 3
SprecherProf. Akira Uedono (University of Tsukuba · School of Science and Engineering)
Veranstalter

MLZ, TUM

MLZ is a cooperation between:

Technische Universität München> Technische Universität MünchenHelmholtz-Zentrum Geesthacht> Helmholtz-Zentrum GeesthachtForschungszentrum Jülich> Forschungszentrum Jülich
Endlich da!
Die MLZ App (Android)
MLZ App> MLZ App