Temperature-dependent terahertz time-domain spectroscopy of MBE-grown single- and multi-layered InAs/GaAs quantum dots
The temperature-dependence of the terahertz emission characteristics of molecular beam epitaxy (MBE)-grown single- and multi-layered InAs/GaAs quantum dots were studied. Results from terahertz time-domain spectroscopy measurements have shown that the THz emission from the multi-layered QD sample is higher than the single-layered QD sample. This is attributed to (i) the presence of more photocarriers available for transport and (ii) more uniform QD size distribution. The THz emission from the samples was also found to increase as temperature increases, suggesting drift-related photo-carrier transport. Temperature- and excitation power-dependent PL spectroscopy were used to assess the optical quality of the single- and Multi-layered QD samples and relate it to the observed THz emission characteristics.