Abstract-Effect of lattice-mismatch strain on electron dynamics in InAs/GaAs quantum dots as seen by time-domain terahertz spectroscopy

Osamu Kojima, Ryo Izumi, Takashi Kita,

http://iopscience.iop.org/article/10.1088/1361-6463/aacae0/pdf


Considering the electron dynamics in the deeper area from the surface is important to improve the efficiency of optoelectronic devices. Potential variations due to InAs quantum dot (QD) growth in the GaAs crystal are investigated via measurements of terahertz electromagnetic waves emitted from the surface. In the pump-energy dependence of the time-domain signal, a phase inversion was observed in the QD sample. In addition, while the signal intensity from the InAs QD sample is maintained in the lower pump energy region, the intensity profile does not show this speci?c change related to the phase inversion. These results demonstrate that the potential change around QDs caused by lattice-mismatched strain can be examined using observations of the time-domain terahertz signal, which can be used to improve the device performance.

Abstract-Noncollinear Electro-Optic Sampling of Terahertz Waves in a Thick GaAs Crystal

Mashkovich, E.A.  Shugurov, A.I. ; Ozawa, S. ; Estacio, E. ; Tani, M. ; Bakunov, M.I.
University of Nizhny Novgorod, Nizhny Novgorod, Russia 
http://ieeexplore.ieee.org/xpl/abstractAuthors.jsp?reload=true&arnumber=7210239&filter%3DAND%28p_IS_Number%3A5741778%29

In this paper, we propose and experimentally demonstrate noncollinear EO sampling of terahertz pulses with a femtosecond fiber laser in cm-thick GaAs crystals. This technique provides more than an order of magnitude improvement in spectral resolution and a significant increase in efficiency as compared to previously used collinear EO sampling in mm- and sub-mm-thick GaAs crystals. 
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