Direct correlation of R -line luminescence with rod-like defect evolution in ion-implanted and annealed silicon
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esearch Letters
Direct correlation of R-line luminescence with rod-like defect evolution in ion-implanted and annealed silicon S. Charnvanichborikarn, Lawrence Livermore National Laboratory, Livermore, California 94550; Department of Electronic Materials Engineering, Research School of Physics and Engineering, The Australian National University, Canberra, ACT 0200, Australia J. Wong-Leung, Department of Electronic Materials Engineering, Research School of Physics and Engineering, The Australian National University, Canberra, ACT 0200, Australia; Centre for Advanced Microscopy, The Australian National University, Canberra, ACT 0200, Australia C. Jagadish and J.S. Williams, Department of Electronic Materials Engineering, Research School of Physics and Engineering, The Australian National University, Canberra, ACT 0200, Australia Address all correspondence to S. Charnvanichborikarn at [email protected] (Received 13 April 2012; accepted 27 July 2012)
Abstract A quantitative correlation between R-line luminescence at around 1.37 µm and {311} defect nature, size and concentration has been undertaken in silicon, following keV Si-implantation and subsequent annealing using photoluminescence spectroscopy and plan-view transmission electron microscopy. The formation and evolution of the rod-like defects were found to be dependent on annealing time at a temperature of 700 °C, but there was no simple correlation found between the density and size of those defects and the R-line intensity. In particular, whereas the presence of {311} defects is essential for observing R-line luminescence, both very small {311} defects at short annealing times and fully developed {311} defects at long annealing times do not contribute to such luminescence. We provide possible explanations for this behavior and suggest that the local (strain) environment around defects, the dopant level and impurities in the silicon substrate may all play a role in determining R-line intensity.
The process of ion implantation in silicon produces damage and defects that usually undergo extensive diffusion, annihilation and agglomeration during heat treatment.[1,2] Some of the residual defects following annealing are optically active when excited by photons or electrons.[3,4] In such cases, the defects give rise to a defect state within the band gap of silicon that allows a direct sub-band gap transition and the emission of light. In particular, the interstitial-based defects (clusters and extended defects) in silicon can be optically active.[3] As the ion-implantation fluence and annealing temperature are raised, the residual defects evolve into interstitial defect clusters, rodlike defects (RLDs) and ultimately dislocations. The tri-Siinterstitial clusters, for example, are thought to be the origin of the W-line emission at 1218 nm.[5–7] The {311} RLDs are associated with R-line luminescence at 1372 nm,[3,8] while dislocations are associated with so-called D-bands at wavelengths above 1500 nm. The {311} RLDs have received much interest in the past decade mai
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