Orthorhombic　tantalum　pentoxide　(β-Ta2O5)　monocrystalline　films　were　deposited　on　epi-GaN/α-Al2O3　(0001)　substrates　using　the　metal-organic　chemical　vapor　deposition　method.　The　prepared　films　were　grown　along　the　β-Ta2O5　(001)　plane.　The　film　deposited　at　850　°C　exhibited　the　best　crystalline　quality　and　the　corresponding　FWHM　of　the　XRD　ω-rocking　curve　for　β-Ta2O5　(001)　plane　was　1.81°.　The　prepared　β-Ta2O5　film　possessed　a　domain　structure,　and　the　growth　mechanism　was　studied　in　detail.　By　the　XRD　Φ　scan　and　HRTEM　analyses,　the　in-plane　epitaxial　relationship　of　the　850　°C-prepared　sample　was　determined　as　β-Ta2O5　[100]　GaN　[1‾100].　The　elemental　composition　and　valence　states　were　studied　and　the　band　gap　of　the　film　prepared　at　850　°C　was　calculated　to　be　4.34　eV　by　the　analysis　of　the　electron　energy　loss　spectrum.　©　2022