Ultrawide-bandgap (6.14 eV) (AlGa)2O3/Ga2O3 heterostructure designed by lattice matching strategy for highly sensitive vacuum ultraviolet photodetection

One judiciously designed strategy of utilizing an ultrathin but conductive Ga2O3:Si nanolayer to prepare (AlGa)2O3 crystalline film is demonstrated. Benefiting from the existence of Ga2O3:Si nanolayer, a high-quality (Al0.68Ga0.32)2O3 sesquioxide film with 68 at.% aluminum was epitaxially grown on sapphire substrates, which was characterized by high-resolution transmission electron microscopy, X-ray photoelectron spectroscopy and X-ray diffraction. Its bandgap was broadened to 6.14 eV, and a vacuum ultraviolet (VUV) (AlGa)2O3/Ga2O3:Si photodetector was subsequently fabricated. The detector exhibits a pretty high on-off ratio of about 103, an open-circuit voltage of 1.0 V and a responsivity of 8.1 mAW−1 at 0 V bias voltage. The performances imply that the proposed strategy is valuable for improving the quality and also adjusting the bandgap of (AlGa)2O3 sesquioxides, which is expected to facilitate their application in VUV photodetection.