Al-Nanoparticle Sensitized β-Ga2O3-Based Solar-Blind Photodetector Fabricated via Focused Ion Beam Micro/Nano Processing

The performance of β-Ga ₂ O ₃ -based solar blind photodetector (PD) has been enhanced apparently by utilizing the effects of localized surface plasmon resonance of Al nanoparticles (Al NPs) array. The size and period of the Al NPs array are determined using the finite-difference time-domain method to obtain optimal resonance absorption with β-Ga ₂ O ₃ in the solar-blind waveband. Al NPs were then fabricated using focused ion beam micro/nano processing on a β-Ga ₂ O ₃ -based metal-semiconductor-metal structure PD. The dark current of the β-Ga ₂ O ₃ structure with Al NPs (β-Ga ₂ O ₃ @Al) is 7.72 × 10 ^-12 A, which is two orders of magnitude lower than that of pure β-Ga ₂ O ₃ (8.01 ×10 ^-10 A). This difference is attributed to the partial oxidation of the Al NPs, which forms Al ₂ O ₃ and passivates the β-Ga ₂ O ₃ interface. In addition, due to the resonance absorption and the hot electrons generated by the interband transition of the Al NPs, the light current increases threefold, resulting in the β-Ga ₂ O ₃ @Al NP PD having a high light-to-dark current ratio of 5.57 ×10 ⁴ . Under a bias of 20 V and 254-nm illumination (44.38 μW/cm ² ), the β-Ga ₂ O ₃ @Al NP PD has high responsivity and detectivity of 131 A/W and 7.17 × 10 ¹⁴ Jones, respectively. Furthermore, owing to the oxide shell Al ₂ O ₃ passivation and the surface plasmons of the Al NPs, the persistent photoconductivity exhibited by the pure β-Ga ₂ O ₃ at rise time is suppressed and the decay time is sped up.