▎ 摘　　要

We have derived a formula for the density of states N(E) of a N-period graphene superlattice (SL), which is given as an integral over the inverse of the absolute value of the group delay velocity vx along the SL-axis. Using that formula, it was shown that N(E) exhibits essentially the same structure for all values of N5. It was found that for E<0, the effects of finite crystal size modify dramatically the density of states of the corresponding infinite SL, whereas for E>0 and N5, it is only slightly modified. According to our results, 1/vx is proportional to the transmission coefficient, which allows us to establish a certain correlation between the properties of N(E) and those of the Landauer conductance GN(E) of the N-period SL. Certainly, GN(E) exhibits a peak structure as a function of E, with local dips located at the same energies as those of N(E). The same behavior was observed for the V-dependence of GN(E) with E=0, which is very similar to that of N(0). When N increases, the peak positions of both GN(0) and N(0) tend to be located at those values of V where new Dirac points appear.