Yi-Jiunn Chien

Free-carrier relaxation and lattice heating in photoexcited bismuth

We report ultrafast surface pump and interface probe experiments on photoexcited carrier transport across single crystal bismuth films on sapphire. The film thickness is sufficient to separate carrier dynamics from lattice heating and strain, allowing us to investigate the time scales of momentum relaxation, heat transfer to the lattice, and electron-hole recombination. The measured electron-hole (

Time- and momentum-resolved probe of heat transport in photo-excited bismuth

e\ensuremath{-}h

Thin-film ferromagnetic semiconductors based on Sb2−xVxTe3Sb2−xVxTe3 with TCTC of 177 K177K

) recombination time is 12--26 ps and ambipolar diffusivity is 18--40 cm

Growth and transport properties of Sb 2- x V x Te 3 thin films on sapphire substrates

{}^{2}

Kapitza conductance of Bi/Sapphire interface measured by time-resolved x-ray diffraction

/s for carrier excitation up to

Ambipolar diffusion and recombination of photoexcited carriers in bismuth films

\ensuremath{\sim}{10}^{19}{\text{cm}}^{\ensuremath{-}3}

Exploring the ferromagnetic phase diagram of Sb2-xVxTe3 and Sb2-xCrxTe3 using hydrostatic pressure as an experimental variable

. By comparing the heating of the front and back sides of the film, we put lower limits on the rate of heat transfer to the lattice, and by observing the decay of the plasma at the back of the film, we estimate the time scale of electron-hole recombination. We interpret each of these time scales within a common framework of electron-phonon scattering and find qualitative agreement between the various relaxation times observed. We find that the carrier density is not determined by the

Transition metal-doped Sb2Te3 magnetic semiconductor thin films.

e\ensuremath{-}h

Transition metal-doped Sb

plasma temperature after a few picoseconds. The diffusion and recombination become nonlinear with initial excitation

_{2}

\ensuremath{\gtrsim}{10}^{20}{\text{cm}}^{\ensuremath{-}3}