Fig. 3
From: Optical charge state control of spin defects in 4H-SiC
Photo-dynamics and modeling in neutral divacancies in 4H-SiC. The charge dynamics is probed using two and three color experiments, following a reset-pump-measure scheme. a Typical decay curves obtained under various reset/pump wavelength and temperatures. The fit (line) is obtained from the model given in d. b Top figure: ratio between pump and 365 nm steady-state PL intensities. Bottom figure: decay rates (normalized to 100 μW at every pump wavelength) obtained by fitting the decays in a with a stretched exponential function (error bars are 95% confidence intervals from the fit). In blue, the sequence starts after 365 nm pumping, while in red, after 976 nm. The lines are given by the model in d, with the area corresponding to 95% confidence intervals. For 1310 nm, no significant decay was observed over 100 s, hence the steady-state values are given without error bars. c Formation energies of the divacancy in 4H-SiC, taken from20. d Model used for simulating all transients in a, b, e, including the VV0 and VV− levels of the divacancy, as well as an unknown trap with two charge states. Processes included in the model are given in the legend. Hole photo-emission converting VV0 to VV− involves a two-photon process, exciting VV0 from its ground state to its excited state, followed by excitation and capture of an electron from the valence band. e Temperature dependence of the steady state after 976 nm pumping (365 nm reset). Error bars are 95% confidence intervals from the decays’ stretched exponential fit. Lines are given by the model in d, corresponding to thermal generation of electron-hole (e-h) pairs. The origin of the intermediate region between 30 and 100 K is unknown. Above 210 K, PL5 and PL6 signals become dominant, making the measurement unreliable as they are UV-insensitive
