Amorphous　Ga2O3　thin　films　were　deposited　on　SiO2　and　sapphire　substrates　by　pulsed　magnetron　sputtering　(PSD)　at　room　temperature,　respectively.　Corresponding　amorphous　Ga2O3　thin　film　photodetectors　were　prepared.　The　oxygen　vacancies　and　defects　of　the　interface　between　films　and　substrates　were　found　to　determine　the　discrepancy　by　comparing　the　performance　between　these　two　photodetectors.　Amorphous　Ga2O3　photodetectors　on　SiO2　had　highly　performances　with　a　responsivity　of　417　A/W,　detectivity　of　7.84　x　1012　Jones,　and　external　quantum　efficiency　of　2.01　x　105　%.