Exciton Control in a Room-Temperature Bulk Semiconductor with Coherent Strain Pulses

Science Advances 5,11, (2019)

Exciton Control in a Room-Temperature Bulk Semiconductor with Coherent Strain Pulses

Edoardo Baldini,Adriel Dominguez,Tania Palmieri,Oliviero Cannelli,Angel Rubio,Pascal Ruello, Majed Chergui

Controlling the excitonic optical properties of room temperature semiconductors using time-dependent perturbations is key to future optoelectronic applications. The optical Stark effect in bulk and low-dimensional materials has recently shown exciton shifts below 20 meV. Here, we demonstrate dynamical tuning of the exciton properties by photoinduced coherent acoustic phonons in the cheap and abundant wide-gap semiconductor anatase titanium dioxide (TiO2) in single crystalline form. The giant coupling between the excitons and the photoinduced strain pulses yields a room temperature exciton shift of 30 to 50 meV and a marked modulation of its oscillator strength. An advanced ab initio treatment of the exciton-phonon interaction fully accounts for these results, and shows that the deformation potential coupling underlies the generation and detection of the giant acoustic phonon modulations.

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Doi
http://dx.doi.org/10.1126/sciadv.aax2937
arxiv
http://arxiv.org/abs/1803.07666

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