  Two-dimensional stanene is a promising candidate material for realizing
room-temperature quantum spin Hall (QSH) effect. Monolayer stanene has recently
been fabricated by molecular beam epitaxy, but shows metallic features on
Bi$_2$Te$_3$(111) substrate, which motivates us to study the important
influence of substrate. Based on first-principles calculations, we find that
varying substrate conditions considerably tunes electronic properties of
stanene. The supported stanene gives either trivial or QSH states, with
significant Rashba splitting induced by inversion asymmetry. More importantly,
large-gap (up to 0.3 eV) QSH states are realizable when growing stanene on
various substrates, like the anion-terminated (111) surfaces of SrTe, PbTe,
BaSe and BaTe. These findings provide significant guidance for future research
of stanene and large-gap QSH states.
