The　ultra-wide　bandgap　(~6.2　eV),　thermal　stability　and　radiation　tolerance　of　AlN　make　it　an　ideal　choice　for　preparation　of　high-performance　far-ultraviolet　photodetectors　(FUV　PDs).　However,　the　challenge　of　epitaxial　crack-free　AlN　single-crystalline　films　(SCFs)　on　GaN　templates　with　low　defect　density　has　limited　its　practical　applications　in　vertical　devices.　Here,　a　novel　preparation　strategy　of　high-quality　AlN　films　was　proposed　via　the　metal　organic　chemical　vapor　deposition　(MOCVD)　technique.　Cross-sectional　transmission　electron　microscopy　(TEM)　studies　clearly　indicate　that　sharp,　crack-free　AlN　films　in　single-crystal　configurations　were　achieved.　We　also　constructed　a　p-graphene/i-AlN/n-GaN　photovoltaic　FUV　PD　with　excellent　spectral　selectivity　for　the　FUV/UV-C　rejection　ratio　of　>103,　a　sharp　cutoff　edge　at　206　nm　and　a　high　responsivity　of　25　mA/W.　This　work　provides　an　important　reference　for　device　design　of　AlN　materials　for　high-performance　FUV　PDs.　©　2022　by　the　authors.