  We demonstrate theoretically the coexistence of Dirac semimetal and
topological insulator phases in InSb/$\alpha$-Sn conventional semiconductor
superlattices, based on advanced first-principles calculations combined with
low-energy $k\cdot p$ theory. By proper interfaces designing, a large interface
polarization emerges when the growth direction is chosen along {[}111{]}. Such
an intrinsic polarized electrostatic field reduces band gap largely and invert
the band structure finally, leading to emerge of the topological Dirac
semimetal phase with a pair of Dirac nodes appearing along the (111)
crystallographic direction near the $\Gamma$ point. The surface states and
Fermi arc are clearly observed in (100) projected surface. In addition, we also
find a two-dimensional topological insulator phase with large nontrivial band
gap approaching 70 meV, which make it possible to observe the quantum spin Hall
effect at room temperature. Our proposal paves a way to realize topological
nontrivial phases coexisted in conventional semiconductor superlattices by
proper interface designing.

Materials Science;Mesoscale and Nanoscale Physics