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

      Researchers from the Songshan Lake Materials Laboratory have published a dissertation titled "Unraveling the role of dangling bonds passivation in amorphous Ga₂O₃ for high-performance solar-blind UV detection" in Chinese Physics B.

Project Support

      Project supported by the National Natural Science Foundation of China (Grant Nos. 62404146, 12174275, and 62174113), the Basic and Applied Basic Research Foundation of Guangdong Province, China (Grant Nos. 2023A1515110730 and 2023A1515140094), and the INTPART Program at the Research Council of Norway (Project number 322382).

Background

      Solar-blind ultraviolet (UV) (200 nm–280 nm) detectors have received widespread attention for their potential application in flame monitoring, corona detection, missile tracking and near-Earth communication. With suitable band gap (∼ 5 eV), stable chemical properties and regulative carrier concentration, Ga₂O₃ is an ideal material for fabricating solar-blind UV detectors. Further, compared with high-temperature epitaxial growth of crystalline Ga₂O₃ thin films, amorphous Ga₂O₃ (a-Ga₂O₃) thin films can achieve low-cost large-area deposition on any substrates. Especially, some recent works have proved that a-Ga₂O₃ owns detection performance comparable to β-Ga₂O₃ counterpart. These features position a-Ga₂O₃ as a suitable material for solar-blind UV detection.

Abstract

      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.