The samples were grown by

The quantum well was achieved by optimizing the As4/Sb4 flux ratio under the MBE growth. Hall effect was measured at room temperature (RT), 77, and 4.2 K to estimate the carrier density. In order to eliminate the persistent-photoconductive effect on a sample, vestigial structures was shielded from irradiation and kept in the dark at room temperature (RT) at least overnight, after setting it on the sample holder.