  We investigate topological phases in two-dimensional Bi/Sb honeycomb crystals
considering planar, buckled, freestanding and deposited on a substrate
structures. We use the multi-orbital tight-binding model and compare results
with density functional theory methods. We distinguish topological phases by
calculating topological invariants, analyze edge states of systems in a ribbon
geometry and by looking at their entanglement spectra. We show that weak
coupling to the substrate of buckled and planar crystals is sufficient to lead
to a transition to the $Z_2$ topological insulator phase. Topological
crystalline insulator (TCI) phase exhibits a pair of edge states in the
semi-infinite geometry and in the entanglement spectrum. Transport calculations
for TCI phases show robust quantized conductance even in a presence of
symmetry-breaking disorder.
