Magento-spectroscopy and transport study of the Kagome patterned two-dimensional electron gas

We fabricate the Kagome pattern (with a pseudo lattice constant of a = 520 nm) on the high mobility (μ = 5x10⁶ cm²/Vs) two-dimensional electron gas (2DEG) in a GaAs/AlGaAs quantum well. The patterned sample displays high-quality transport features that exhibit a zero Hall plateau (in R_xy) and geometric resonances (in R_xx) at low magnetic fields. In our magneto-photoluminescence (PL) measurements, the transitions from the valence band to the conduction band are excited with the laser with a wavelength of 633 nm, and are detected with a fluorescence spectrometer. At temperatures below 60 K, we observe a very robust peak of PL at around E = 1817 meV (P1), which exists only in the Kagome patterned area. The intensity of P1 is qualitatively consistent with the trend of longitudinal resistance. In the spectroscopic range of ~ 1720 – 1800 meV discrete tiny peaks are observable, which are attributed to the transitions between the different branches of the excited energy bands. Thus, the physics of the flat band from the Kagome structure can be detected and characterized via PL detection. Moreover, the spectroscopic measurements exhibit extraordinarily high PL efficiency which is much larger than that in GaAs bulk and excitations.