Fig. 3: Ionisation behaviour of single V2 centre under PLE and two-colour laser irradiation.
From: Single V2 defect in 4H silicon carbide Schottky diode at low temperature
a Ionisation rate γ under resonant laser irradiation versus PLE laser power shows almost identical results for two different bias voltages (inset shows line slope Γ for various voltages and a decreasing trendline (blue) for lower voltages). γ is determined by sweeping the ionisation pulse length τ and extracted using an exponential fit. b Two colour absorption power-dependent ionisation rate Γ (slope of γλ) versus wavelength (error bars \(\widehat{=}\pm 1\sigma\)). Second laser pulse (varied in length, wavelength and power) is applied together with PLE lasers at low power. Fit with Fermi distribution yields a threshold of 948 nm for the charge conversion of \({{{{\rm{V}}}}}_{{{{\rm{Si}}}}}^{-}\) to \({{{{\rm{V}}}}}_{{{{\rm{Si}}}}}^{2-}\), compare (c). Schematic pulse sequences for (a, b) shown on top. Inset: exemplary ionisation rate γ versus power of second laser for a wavelength of λ = 900 nm again linearly fitted. All error bars are equivalent to ± 1σ. c Defect level and charge state transition level picture of the cubic silicon vacancy centre within the band gap (3.26 eV used). Values for the (−/2−)-transition taken from ref. 7, the other values are deduced from that. d Ab-initio calculation of the photon absorption cross-section for the charge transition (−/2−) of V2, recalculated to a photo-ionisation rate ΓPI (more detailed information in Supplementary Note 4). Similar wavelength dependence is visible like for measured data in (b).
