Figure 3. Germanium (100), fast depolarization rate Λ_f, CrysTec sample.

(a), Λ_f at temperature T = 220 K as a function of time after terminating the illumination with white LEDs at 10 mW/cm² for 5 h. The solid line is a fit of the exponential function exp(−t/τ_D), where t is the time and τ_D the time constant of the decrease of Λ_f. The fit yields τ_D = 16.7 ± 5.5 h, which corresponds to a half-life of about 12 h. The error indicates the standard deviation of the fit result. (b), Arrhenius plot of Λ_f between 270 K and 280 K. Fit function is Λ_f(T) = C exp(E_A/k_BT), where C is a constant, E_A = 1.1 ± 0.3 eV is the activation energy, and k_B is the Boltzmann constant.