Two-dimensional　(2D)　ferroelectric　field-effect　transistors　(Fe-FETs)　have　attracted　extensive　interest　as　a　competitive　platform　for　implementing　future-generation　functional　electronics,　including　digital　memory　and　brain-inspired　computing　circuits.　In　2D　Fe-FETs,　the　2D　ferroelectric　materials　are　more　suitable　as　gate　dielectric　materials　compared　to　3D　ferroelectric　materials.　However,　the　current　2D　ferroelectric　materials　(represented　by　alpha-In2Se3)　need　to　be　integrated　with　other　3D　gate　dielectric　layers　because　of　their　high　conductivity　as　a　ferroelectric　semiconductor.　This　2D/3D　hybrid　structure　can　lead　to　compatibility　problems　in　practical　devices.　In　this　study,　a　new　2D　gate　dielectric　material　that　is　compatible　with　the　complementary　metal-oxide　semiconductor　process　was　found　by　using　oxygen　plasma　treatment.　The　2D　gate　dielectric　material　obtained　shows　excellent　performance,　with　an　equivalent　oxide　thickness　of　less　than　0.15　nm,　and　excellent　insulation,　with　a　leakage　current　of　less　than　2　x　10(-5)　A　cm(-2)　(under　a　1　V　gate　voltage).　Based　on　this　dielectric　layer　and　the　alpha-In2Se3　ferroelectric　gate　material,　we　fabricated　an　all-2D　Fe-FET　high-performance　photodetector　with　a　high　on/off　ratio　(similar　to　10(5))　and　detectivity　(＞10(13)　Jones).　Moreover,　the　photoelectric　device　integrates　perception,　memory　and　computing　characteristics,　indicating　that　it　can　be　applied　to　an　artificial　neural　network　for　visual　recognition.