Hexagonal　tantalum　pentoxide　(delta-Ta2O5)　single-crystalline　films　were　synthesized　on　Yttrium　Vanadate　(YVO4)　(100)　by　metalorganic　chemical　vapor　deposition　(MOCVD)　and　post　annealing　process.　The　film　annealed　at　900　degrees　C　exhibited　single　crystal　structure　with　the　best　crystalline　quality.　The　heteroepitaxial　relationship　was　determined　as　delta-Ta2O5　(0001)parallel　to　YVO4　(100)　with　delta-Ta2O5　[(1)　over　bar2　(1)　over　bar0]parallel　to　YVO4　[010]　by　the　analysis　of　lattice　structure.　A　diagrammatic　sketch　was　proposed　to　illustrate　the　growth　mechanism.　For　the　best　delta-Ta2O5　single-crystalline　film,　the　band　gap　was　estimated　to　be　4.33　eV　and　the　average　transmittance　in　the　visible　range　exceeded　92%.