Cubic Gd2O3 heteroepitaxial thin film fabricated via pulsed laser deposition: Structure and deep-UV photodetector

Abstract

Aiming at the current research gaps in Gd2O3 single-crystal films and detection below 250 nm of UV light for Gd2O3-based photodetectors (PDs), this study employed pulsed laser deposition under a laser frequency of 6 Hz to successfully a grow cubic (c-) Gd2O3(222) epitaxial film on a GaN(0001) substrate. The epitaxial film had a wide optical bandgap (5.4 eV), a large electronic bandgap (5.16 eV), and a c-Gd2O3⟨011¯⟩ ǁ GaN [21¯1¯0] in-plane epitaxial relationship with the substrate. The PD fabricated based on the film presented excellent response characteristics to UV light below 250 nm, with a rejection ratio (R202 nm/R300 nm) up to 102. Under 222 nm deep-UV light, the PD exhibited excellent detection performance with a high photoresponsivity of 0.801 A/W under 5 V, and a fast response speed (rise time: 0.27 s; fall time: 0.28 s). This work provides a feasible approach for fabricating high-performance Gd2O3 epitaxial film PDs, laying a foundation for their applications in solar-blind deep-UV sensing systems.