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

摘要

Considering the electron dynamics in a 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 specific 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.