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 ($N_s$) 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 $N_s<5\times 10^9$ cm$^{-2}$. Thus, the two-dimensional semimetal under study does not exhibit the $N_s$-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.