Electrophoretic Deposition of Conformal β‑Ga₂O₃ Films on Arbitrary Substrates for Heterojunction-Based Deep-Ultraviolet Photodetectors

The ultrawide bandgap semiconductor β-Ga₂O₃ has huge potential for the design of deep-ultraviolet (UV) photodetectors and nanoscale high-power electronic applications. The present study for the first time demonstrates the deposition of dense β-Ga₂O₃ films on arbitrary substrates (rigid vs flexible, conducting vs insulating) using a simple and cost-effective electrophoretic deposition (EPD) process. Structural characterization of the as-deposited β-Ga₂O₃ films on transparent fluorine-doped tin oxide (FTO), technologically feasible silicon, flexible metallic-aluminum foil, and indium tin oxide-coated polyethylene terephthalate (ITO-PET) substrates shows polycrystalline behavior and reveals the formation of isotype and metal–semiconductor–metal heterojunctions. EPD on a patterned aluminum microgrid array on an insulating glass substrate reveals conformal deposition. The as-deposited β-Ga₂O₃ films reveal low dark currents of less than 12 nA on all the substrates, with photo-to-dark current ratio (PDCR) values of 7.08, 2.08, and 4.51 for FTO, silicon, and flexible aluminum foil, respectively, upon UV lamp exposure. The simple cost-effective one-step EPD process with an extremely fast deposition rate of approximately 1.5 μm/min offers a high-throughput method for large-scale synthesis of conformal polycrystalline β-Ga₂O₃ films on arbitrary substrates in any geometry for the creation of isotype and other heterojunction-based deep-UV photodetector applications.