Analysis of positron beam data by the combined use of the shape- and wing-parameters

TLDR

An improved approach is presented for analyzing positron beam Doppler broadening data. Instead of analyzing the energy‑dependent shape parameter S(E) alone, the method plots both S(E) and wing W(E) as a trajectory in the S–W plane using implantation energy as a running parameter, and illustrates its advantages and limitations on three test cases (He‑implanted silicon, a MOS system under bias, and a bare oxide layer on silicon). The S–W trajectory plot enables qualitative interpretation of the data and allows independent determination of characteristic shape and wing parameters for different positron trapping layers without numerical simulation or fitting.

Abstract

An improved approach is presented for the analysis of positron beam Doppler broadening data. Instead of analyzing the energy-dependent shape parameter, the so-called S(E) data, we combined the shape S(E) and wing W(E) data by plotting them as a trajectory in the S–W plane, using the implantation energy as a running parameter. It is shown that this plot is of particular interest for the qualitative interpretation of the data. Furthermore, it allows the independent determination of the characteristic shape and wing parameters of the different positron trapping layers without the use of a numerical simulation and fitting program. The method and its advantages and limitations are illustrated for three cases: a silicon sample implanted with helium, a metal–oxide–silicon system subjected to a bias voltage and a bare oxide layer on silicon.