Center for Relativistic Laser Science

2017 119th KCS Meeting

The colloidal quantum dots(CQDs) can be utilized in laser source, LEDs, quantum computation and many more. Especially, the intraband transition of CQDs is in the spotlight because it allows reaching mid-IR regime and it can be used for MIR laser sources or photoedetector. Unfortunately, its application is limited by too fast decay of excited states of CQDs which is usually explained by Auger processes. In these days, there are opinions that this fast decaying is from not only the Auger process but also the electron cooling. In our work, we did IR pump-probe measurements of HgS Quantum dots. To study the dynamics of pure conduction band, the electronic doping of HgS CQDs was done by using organic ligand(Oleylamine). Therefore, our observation is confined in intraband transition of conduction band and there will be no trap states. Interestingly, the results show wavelength(or size)-independent, sub-ps dynamics and interesting decaying pattern. We believe this result can be explained by cooling-down of hot electron.