Atom location and ion damage studies of gold hyperdoped silicon via ion implantation followed by pulsed laser melting

(1) Australian National University
(2) Massachusetts Institute of Technology
(3) Harvard University

Previously, we have demonstrated that silicon hyperdoped by gold through ion implantation followed by pulsed laser melting (PLM) shows enhanced absorption in the infrared, making it a promising material for photodetector devices [1]. It has been hypothesized that this enhanced absorption relates to discrete sub-band gap levels introduced by substitutional gold in silicon, though this relationship is not yet quantified. We note also that high concentrations of gold may lead to cellular breakdown via solute partitioning during rapid solidification following PLM [2].  To optimise device performance, we employ Rutherford backscattering spectrometry combined with channeling (RBS/C) to determine the degree of substitutionality for supersaturated gold of different doses, implant conditions and laser powers. Angular scans from major axes were undertaken for precise atom location. Furthermore, we investigate the mechanism of cellular breakdown and its impact on optical absorption by combining RBS and transmission electron microscopy analysis.  Finally, we explore the effect of excessive helium ion damage during the RBS-channeling analysis on the atom location of the metastable supersaturated gold in silicon.  

[1] J. P. Mailoa et al., Nature Communications 5, 3011 (2014)
[2] D. Recht et al., Journal of Applied Physics 114, 124903 (2013)