Growth of Low-defect Si-Doped Ga₂O₃ Film on Fluorine-doped Tin Oxide Substrate for Self-powered and High-performance Ultraviolet Photodetector

Abstract

In this study, an efficient ultraviolet photodetector (UV PD) is prepared based on a p–n junction that is metal-electrode-free and with a vertical configuration. Briefly, n-type Si-doped Ga2O3 was grown by using RF sputtering, and p-type [9,9-dioctylfluorene-co-N-[4-(3-methylpropyl)]-diphenylamine] was deposited by using a spin-coating process. We utilized a very thin TiO2 compact layer, covered on the fluorine-doped tin oxide (FTO)/glass, to modify the morphology of the FTO surface for supporting the growth of the Si-doped Ga2O3 film. Therefore, a Si-doped Ga2O3 film with a low number of defects was formed. The self-powered PD exhibited a comparative performance with high responsivity (R = 1.02 mA/W) and a good on/off ratio of 242.56. In addition, the device performance can be significantly improved when a reverse bias is applied. Under −1 V bias, the responsivity and specific detectivity of the PD achieved 2.31 mA/W and 6.7 × 1010 Jones, respectively. Moreover, the device showed a fast response speed (trise = 122 ms, tfall = 241 ms) and stable photoresponse under 254 nm UV illumination. This finding is expected to facilitate the production of cost-effective UV PD for many applications.