Terahertz time-domain spectroscopy of MBE-grown GaAs/AlGaAs asymmetric double quantum wells
We study the THz emission characteristics of molecular beam epitaxy-grown GaAs/AlGaAs coupled (CADQW) and uncoupled asymmetric double quantum wells (UADQW). We found the THz emission from the CADQW and UADQW samples to be comparable to the THz emission from p-InAs and higher than p-GaAs and n-GaAs. Furthermore, we observe higher THz emission from the CADQW as compared to the UADQW. This is attributed to the tunneling of electrons in the CADQW leading to a larger dipole moment. These results are important for the development of double quantum wells as possible intense THz radiation sources.