Unraveling the role of dangling bonds passivation in amorphous Ga₂O₃ for high-performance solar-blind UV detection

Low-cost and large-area uniform amorphous Ga₂O₃ (a-Ga₂O₃) solar-blind ultraviolet (UV) detectors have garnered significant attention in recent years. Oxygen vacancy (V_O) defects are generally considered as the predominant defects affecting the detector performance. Reducing V_O concentration generally results in both low dark current and low photo current, significantly limiting further improvement of the photo-to-dark current ratio (PDCR) parameter. Herein, a delicately optimized atomic layer deposition (ALD) method is revealed having the capability to break through the trade-off in a-Ga₂O₃, achieving both low dark current and high photocurrent simultaneously. For a clear demonstration, a-Ga₂O₃ contrast sample is prepared by magnetron sputtering and compared as well. Combined tests are performed including x-ray photoelectron spectroscopy, photoluminescence, electron paramagnetic resonance and Fourier-transform infrared spectroscopy. It is found that ALD a-Ga₂O₃ has a lower V_O concentration, but also a lower dangling bonds concentration which are strong non-irradiation recombination centers. Therefore, decrease of dangling bonds is suggested to compensate for the low optical gain induced by low V_O concentration and promote the PDCR to ∼2.06 × 10⁶. Our findings firstly prove that the dangling bonds also play an important role in determining the a-Ga₂O₃ detection performance, offering new insights for further promotion of a-Ga₂O₃ UV detector performance via dual optimization of dangling bonds and V_O.