The　experimental　realization　of　large-scale,　homogeneous　semiconducting　films　with　a　single-layer　thickness　is　of　major　importance　for　next-generation　devices.　Especially　in　view　of　the　compatibility　with　state-of-the-art　semiconductor　technology,　Si-based　monolayer　crystals　are　of　particular　interest.　Here,　the　successful　epitaxial　growth　of　monolayer　Si2Te2　(ML-Si2Te2)　films　on　semiconducting　Sb2Te3　thin　film　substrates　is　reported.　High-quality　(1　x　1)　ML-Si2Te2　films　with　a　coverage　as　high　as　95%　are　obtained　as　revealed　by　scanning　tunneling　microscopy.　X-ray　photoelectron　spectroscopy　confirms　the　existence　of　the　Si-Te　bonds　in　the　obtained　films.　By　combining　scanning　tunneling　spectroscopy　with　density　functional　theory　calculations,　the　existence　of　a　semiconducting　bandgap　is　demonstrated　on　the　order　of　370　meV　for　the　ML-Si2Te2　films　which　reside　in　an　important　mid-infrared　spectral　range.　The　results　pave　the　way　for　practical　applications　of　this　novel　artificial　two-dimensional　material.