ZnO Thin Film-Enhanced Solar-Blind Ultraviolet Photodetection in β-Ga2O3 and Its Application for Highly Sensitive Albumin Detection

To address the low carrier separation efficiency and insufficient response of pristine β-Ga 2 O 3 -based solar-blind ultraviolet photodetectors, a low-cost, non-vacuum heterostructure strategy was proposed. β-Ga 2 O 3 thin films were prepared by mist chemical vapor deposition, and ZnO layers were deposited via successive ionic layer adsorption and reaction to construct an Au/β-Ga 2 O 3 /ZnO/Au heterojunction photodetector. Material characterization verified a clean heterointerface without impurity phases, and the built-in electric field significantly promoted carrier separation. Under 254   nm illumination at 40   V bias, the device delivers a photocurrent of 3.94 μA, 20 times higher than the pristine β-Ga 2 O 3 detector. The responsivity reaches 10.98   A/W, detectivity is 3.69×10 12 Jones, and external quantum efficiency is up to 5.36×10 3 %, enhanced by 20, 19, and 23 times respectively, with markedly improved rise speed and stable switching response. Moreover, the device shows a good linear relationship (R 2 =0.98115) between photocurrent response and bovine serum albumin concentration, enabling highly sensitive protein detection. This work provides a low-cost route for high-performance β-Ga 2 O 3 solar-blind photodetectors and extends their application to rapid, non-destructive UV biosensing.