Two-Dimensional Semimetal HgTe in 14-nm-Thick Quantum Wells

A two-dimensional semimetal is discovered in the (013) HgTe quantum well with a thickness of d = 14 nm, which is much smaller than those previously studied. It is found that such semimetal is characterized by the same band overlap as the wells with d =18−22 nm having the same orientation, but here the impurity scattering of both electrons and holes is much more pronounced. The electron cyclotron photoresistance is measured as a function of the electron density (Ns) and it is shown that the amplitude of the electron cyclotron photoresistance decreases with decreasing density, and the electron cyclotron photoresistance is not detected at Ns < 5 × 109 cm−2. Thus, the two-dimensional semimetal under study does not exhibit the Ns-independent electron cyclotron photoresistance, which was earlier observed in the two-dimensional semimetal arising near the (100) surface. This is assumingly due to a significantly lower (by more than an order of magnitude) electron mobility in the system under study.