Untitled

Abstract

This paper reports on recent advances in the application of electron emission channeling to studies of the lattice location of radioactive probe atoms in semiconductors. The introduction of position-sensitive electron detection has resulted in an improvement in the experimental efficiency of this method by two orders of magnitude. Electron emission channeling now allows to carry out detailed lattice location studies, and is especially interesting for cases where conventional ion beam lattice location techniques can not be applied due to a lack of sensitivity. Characteristic features of electron emission channeling with position-sensitive detection are discussed and illustrated by results on the lattice location of Er in Si and GaAs, and on the lattice sites and stability of implanted transition metals in Si.

Lattice sites of implanted Fe in Si

“…30 and some computational details on its implementation for Si can be found in Ref. 34. To approximate the continuous ␤ − energy spectrum of 59 Fe, simulations were done for electron energies from 50 keV to 450 keV in steps of 25 keV, and the results averaged according to the theoretical spectral ␤ − distribution.…”

“…The fit procedures used in order to compare theoretical yields and experimental patterns take into account the angle resolution of the detection setup and have been described in detail previously. 34,35 Note that as a general rule in fitting any emission channeling FIG. 1.…”

“…30,34,38 Provided that the scattering background and the depth profile of emitter atoms is accurately known and there is no enhanced dechanneling due to defects in the crystal, the isotropic component reflects the fraction of emitter atoms on so-called random ͑R͒ sites, which are sites in heavily damaged surroundings or sites of very low crystal symmetry. Consequently, inaccurate knowledge of the scattering background or emitter depth profile will lead to inaccuracies in assessing the fraction of emitter atoms on R sites.…”

Precise lattice location of substitutional and interstitial Mg in AlN

“…In this letter, we report on direct lattice location studies of implanted Mg in AlN. Using the β − emission channeling technique, [20][21][22][23] we are able to precisely probe the lattice sites occupied by radioactive impurities in single crystalline samples. Following the decay of the radioactive probes, the emitted β − particles experience channeling and blocking effects imposed by the periodic arrangement of the positive nuclei of the single crystal.…”

“…4,14 Quantitative information is obtained by fitting the experimental emission yields with theoretical patterns for the various possible lattice sites, calculated using the manybeam formalism for electron channeling. 20,22 Experimental and theoretical data on the crystallographic structure of AlN and the RT root mean square (rms) displacements of Al and N atoms can be found in Refs. 26-28.…”