Exciton control in a room temperature bulk semiconductor with coherent strain pulses.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 31819899.
- Also identified by DOI 10.1126/sciadv.aax2937 and PMC identifier 6884413.
- Licence recorded as CC BY-NC.
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Abstract
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 (TiO<sub>2</sub>) 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.