Dopant effects on the photoluminescence of interstitial-related centers in ion implanted silicon

Abstract

The dopant dependence of photoluminescence (PL) from interstitial-related centers formed by ion implantation and a subsequent anneal in the range 175-525 C is presented. The evolution of these centers is strongly effected by interstitial-dopant clustering even in the low temperature regime. There is a significant decrease in the W line (1018.2 meV) PL intensity with increasing B concentration. However, an enhancement is also observed in a narrow fabrication window in samples implanted with either P or Ga. The anneal temperature at which the W line intensity is optimized is sensitive to the dopant concentration and type. Furthermore, dopants which are implanted but not activated prior to low temperature thermal processing are found to have a more detrimental effect on the resulting PL. Splitting of the X line (1039.8 meV) arising from implantation damage induced strain is also observed. V

Insights on the atomistic origin of X and W photoluminescence lines inc-Si fromab initiosimulations

“…Photoluminescence measurements indicate that the W line intensity is maximized after annealing in the range 250 − 300 • C and vanishes upon annealing at ∼ 500 • C [5,6]. As the W line intensity diminishes in PL spectra, the X line raises and reaches maximum intensity after annealing in the range 400−500 • C and vanishes upon annealing at ∼ 600 • C [5,6,8].…”

“…As the W line intensity diminishes in PL spectra, the X line raises and reaches maximum intensity after annealing in the range 400−500 • C and vanishes upon annealing at ∼ 600 • C [5,6,8]. The temperature regime at which their presence is maximized along with the fact that their intensity decreases as the damage concentration increases suggest that defects responsible for these lines should be of small size [7,8].…”

“…The centers responsible for these lines are present in ion-implanted [5,6,7,8,9] as well as in high energy electron-and proton-irradiated c-Si [10,11]. As W and X centers are generated during irradiation processes, they coexists with a large variety of defects which makes their identification through experiments difficult.…”

W and X Photoluminescence Centers in Crystalline Si: Chasing Candidates at Atomic Level Through Multiscale Simulations

“…Also, the possibility of converting Si into a sub-bandgap light-emitter semiconductor based on the introduction of PL centers has been explored [4,5]. Among the PL lines with unclear origin, the W (1018 meV) and the less intense X (1040 meV) lines are observed after implantation at low dose, and their intensity can be maximized after subsequent thermal annealing or irradiating at elevated temperature (250-500 • C) [6,7].…”

“…This had been attributed to the formation of additional radiative [11] or non-radiative recombination centers [12] that compete in the capture of photogenerated carriers with the PL centers that existed on undoped samples. Despite this complex scenario, some features about defects responsible for W and X lines are known from experiments: they consist of Si self-interstitial clusters (I n ) [6,7], the W center has trigonal symmetry while the X center has tetragonal symmetry [1][2][3], and their high energy local vibrational modes (LVMs) have been measured [1][2][3]13]. In this work we use a multiscale simulation approach for exploring the possible structure of defects responsible for W and X lines through the comparison of these experimental evidences with the appropriate simulation technique.…”