Full text loading...
Normalized transient transmission signals as a function of delay time at several excitation energies with a photoexcited carrier density of for (a) sample A and (b) sample B.
(a) Calculated DOS (dotted line) and electron distribution function (solid lines) in the conduction band with effective electron and hole masses of and . The effective bandgap energy is estimated from photoluminescence spectra using the FERB model. and indicate the absorption edges. The photogenerated electron distribution excited at 0.775 eV is also shown schematically. (b) Schematic of the DOS (red curves) and electron distribution function (black curves) after thermalization. The BGR causes an increase in the DOS, while the BF decreases the number of unoccupied electron states. Three horizontal lines indicate the different probe photon energies. At higher energy BGR dominates BF, at medium energy BGR and BF cancel out each other, and at lower energy BF dominates BGR. Note that the schematic balance point is located at a lower energy than the actual balance energy, because the BGR effect is exaggerated.
The square of the absorption coefficient against the photon energy. The solid lines indicate linear fits to the curves. The extrapolated absorption edges are approximately 0.64 and 0.7 eV for samples A and B, respectively.
(a) The induced absorption signals at 0.918 eV for sample A with photoexcited carrier density from to . (b) The decay curves at 0.886 eV for sample A with photoexcited carrier density from to . All curves have no slow components.
Article metrics loading...