1：Experimental Design and Method Selection:

The study involves the synthesis of (AlGa)2O3 films on GaN substrates using metal organic chemical vapor deposition (MOCVD) method, followed by the fabrication of graphene/(AlGa)2O3/GaN photovoltaic detectors. The photoelectric properties of the devices are then characterized under various conditions.

2：Sample Selection and Data Sources:

(AlGa)2O3 films were grown on GaN substrates. Commercial graphene was selected for the fabrication of the devices. The materials were characterized using X-ray diffractometer, SEM, EDS, X-ray photoelectron spectroscopy, and UV-visible spectrophotometer.

3：List of Experimental Equipment and Materials:

MOCVD equipment, X-ray diffractometer (Panalytical, Empyrean3 DY02394), ZEISS AURIGA for SEM, ESCALAB 250XiThermo Fisher for XPS, Shimadzu UV-2501PC/2500 UV-visible spectrophotometer, Keysley 6517B source meter, 200 W deuterium lamp (L11798 (Hamamatsu)), deep-UV monochromator of iHR320 (HORIBA), VXUV20A photodetector (PTO Diode Corp).

4：Experimental Procedures and Operational Workflow:

(AlGa)2O3 films were grown on GaN substrates, graphene was transferred to the film surface, and devices were fabricated with Ti/Au top electrodes and In bottom electrodes. Photovoltaic effect and temperature-varying photoelectric tests were conducted under deep-UV illumination.

5：Data Analysis Methods:

The photoelectric properties of the devices were analyzed, including photoresponsivity, response speed, and performance at high temperatures. The formation energy of oxygen vacancy defects and the interface barrier height were calculated using Vienna Ab-initio Simulation Package (VASP) in the frame of DFT.