High Responsivity Flexible β-Ga ₂ O ₃ /IGZO Ultraviolet Photodetectors Enabled by Zr-Modulated Quasi-Two-Dimensional Electron Gas Interfacial Confinement

Quasi-two-dimensional electron gas (quasi-2DEG), with unique quantum confinement and high electron mobility, holds transformative promise for flexible Ga2O3-based heterojunction ultraviolet photodetectors (UVPDs). However, the intrinsic contradiction between flexible-limit temperature and crystalline quality induces oxygen vacancy (VO) related recombination in amorphous Ga2O3, suppressing quasi-2DEG formation and crippling UVPDs’ performance. Herein, we devise a Zr-modulated interface engineering strategy, where Zr-doped β-Ga2O3 (ZrGaO) films with ultralow VO concentrations are synergistically integrated with indium gallium zinc oxide (IGZO) to construct flexible heterojunction UVPDs. Zr incorporation effectively passivates interfacial defects while inducing favorable band alignment, thereby successfully facilitating the formation of a quasi-2DEG at the interface. Notably, the quantum confinement effect resulted in a significant 2.1-fold increase in carrier mobility, enabling a synergistic improvement in carrier transport efficiency and photogenerated electron–hole separation. Ultimately, the device demonstrates exceptional performance metrics under 254 nm illumination: an ultrahigh photo-to-dark current ratio of 1.37 × 105, remarkable responsivity of 1.65 × 102 A W–1, and detectivity reaching 1.06 × 1014 Jones, surpassing most reported flexible UVPDs. Furthermore, the flexible device retained stable optoelectronic performance after 1,000 bending cycles under varying angles, demonstrating exceptional mechanical durability. This work demonstrates the potential of Zr-modulated interface engineering in inducing quasi-2DEG effects for flexible optoelectronics, establishing a scalable design strategy for next-generation high-performance wearable UV detection systems.