【Epitaxy Papers】Improved performance of solar blind ultraviolet photodetectors by spatial ALD Zn-doped Ga₂O₃ film and post-annealing

      Researchers from the Xiamen University of Technology have published a dissertation titled "Improved performance of solar blind ultraviolet photodetectors by spatial ALD Zn-doped Ga₂O₃ film and post-annealing" in Surface and Coatings Technology.

Abstract

      In this study, Zn-doped gallium oxide (Ga₂O₃) films are prepared using spatial atomic layer deposition (sALD) at 150 °C. The trimethylgallium and diethylzinc (DEZ) are co-injected to promote random Zn incorporation, with the DEZ flow rate varied to attain different doping levels. The experimental results indicate that the actual Zn content can be predicted by the DEZ output flow rate ratio with an acceptable deviation. The Zn content in the as-deposited sALD films ranges from 0 to 8.2 at.% with a significant portion of the Zn dopants existing as interstitials. It is found that oxygen vacancies are suppressed when Zn interstitials become predominant over Zn substitutionals. Post-annealing in an oxygen atmosphere at 600 °C can substantially mitigate the concentration of oxygen vacancies and Zn interstitials. The annealed film prepared with a DEZ flow rate of 75 sccm, which contains a moderate amount of Zn interstitials, achieves both a remarkably low oxygen vacancy ratio of 7.2 % and an undeteriorated crystalline structure. The 100 nm-thick sALD Zn-doped film prepared at the DEZ flow rate of 75 sccm is applied to UV photodetectors, demonstrating an exceptionally low dark current of 7.1 × 10⁻¹³ A, a remarkable on/off current ratio of 7.4 × 10⁶, along with a satisfactory external quantum efficiency of 305 %, responsivity of 0.76 A/W, and a fast response time of 0.08 s. These results indicate that improved film quality can be achieved through sALD co-injection in conjunction with post-annealing, facilitating the application of sALD technology in advanced, cost-effective, and high-performance ultraviolet photodetectors.

DOI：

https://doi.org/10.1016/j.surfcoat.2025.131798