Probing interfacial states in β-Ga2O3/SiO2 TFTs for high-response broad-band photodetection

Mechanically exfoliated β-Ga2O3 flakes preserve bulk material's single crystallinity for easy integration but suffer from interfacial defects that greatly influence device performance. In this paper, we report a quantitative characterization of interfacial states in phrase β-Ga2O3/SiO2 thin-film transistors and then propose their beneficial application in achieving high-response broad-band photodetection. Photo-excited charge collection spectroscopy technique was employed to probe the interfacial states, revealing a substantial density (∼4 × 1012 cm−2 eV−1) of deep-level states ranging from 2.5 to 3.7 eV below the conduction band. Intriguingly, a photoresponsivity as high as 2 × 104 A/W was achieved via utilizing these interfacial states, along with the tunable broad-band response ranging from 335 to 496 nm. This research enhances both the well-industrialized silicon devices and the emerging β-Ga2O3 technologies. Furthermore, it introduces a profound concept: defects, once seen as flaws, can be assets when their characteristics are thoroughly understood.