Origin and perspectives of the 1.54 μm luminescence from ion-beam-synthesized β-FeSi2 precipitates in Si

Abstract

The structural and optical properties of β-FeSi2 precipitates in Si have been analyzed. Float zone Si samples were implanted at 250 °C with 350 keV Fe ions to fluences in the range 1–5×1015/cm2 and annealed in vacuum at 800 °C for times up to 24 h. Detailed morphological analyses of these samples, using transmission electron microscopy, reveal the presence of (i) a band of small (with a diameter <30 nm) highly strained β-FeSi2 precipitates centered at a depth of ∼150 nm, (ii) a band of large (>100 nm diameter) fully relaxed β-FeSi2 precipitates centered at a depth of ∼320 nm, and (iii) residual extended defects. A sharp photoluminescence peak at 1.54 μm is measured at 17 K. This peak remains unchanged when the region containing the small precipitates is removed, using Ar sputtering. On the other hand, it is also fully suppressed when the large precipitates region is removed and a high concentration of extended defects remains in the samples. This allowed us to identify the large unstrained precipitates as the main sources of the 1.54 μm luminescence. Finally, we found that carrier recombination within iron precipitates is characterized by a weak oscillator strength resulting in a long decay lifetime of the 1.54 μm signal at 17 K (∼60 μs) and in a strong temperature quenching of the luminescence yield.

Sulphur doped silicon light emitting diodes

“…Emission at 1.54 pm has been reported from the beta phase o f FeSi2 (p-FeSi2) [32,33,34]. Again, the above emission was observed at low temperatures (^ 80 K) and was very weak at room temperature.…”

“…Another evidence for the origin o f the 1.54 pm luminescence from p-FeSi2 has been reported by C. Spinella et al, [34]. Iron was implanted into n-type silicon wafers at 350 keV and 250 °C, at fluences ranging between 1-5 x 10^^ ions/cm"^, followed by amiealing at 800 for up to 24 hours.…”

Growth of β-FeSi2 particles on silicon by reactive deposition epitaxy

“…Paraskevopoulos). region at 77 K compared to the continuous ␤-FeSi 2 layers or ␤-FeSi 2 single crystals [13,14]. Several methods, such as solid phase epitaxy (SPE) [15], reactive deposition epitaxy (RDE) [16,17] and Fe ion implantation [6,18] have been used to grow ␤-FeSi 2 nanoislands on Si substrates.…”

Light emission from silicon: Some perspectives and applications

“…47 As with Er-doped Si LEDs (forward biased), the quantum efficiency is probably insufficient (Ͻ0.01% at room temperature) for general applications, owing to high nonradiative recombination at room temperature in these defect systems. 48,49 …”