Characterization of InAs/GaAs quantum dots utilizing THz time-domain spectroscopy

We have investigated the carrier capture behavior of n-type modulation-doped InAs/GaAs QDs using THz time-domain spectroscopy (THz TDS) in order to estimate the total number of electrons captured by the QDs. The THz transmission of the sample with QDs (#1) is larger than that of the sample without QDs (#2). From the THz waveforms and subsequent analysis, the #1 sample shows lower conductivity which is resulted from the smaller number of free carriers due to the capture by the QDs.