High‐Performance <i>ε</i> ‐Ga ₂ O ₃ Photodetectors Based on Two‐Step Growth to Expand Carrier Transport Paths for Solar‐Blind Imaging Applications

ABSTRACT ε Ga 2 O 3 is considered a promising candidate for fabricating high‐performance solar‐blind photodetectors (SBPDs) due to its excellent thermal stability, compatibility with heterogeneous integration, and the capacity for achieving high gain through defect engineering. In the future, there is an urgent need to design and fabricate Ga 2 O 3 ‐based photodetectors with high sensitivity for practical applications. Herein, we firstly present a two‐step growth to enhance the performance of ε ‐Ga 2 O 3 ‐based SBPDs. The fabricated SBPDs based on these films achieve a high specific detectivity of 2.79 × 10 16 Jones, a responsivity of 407.5 A W −1 , and a fast response speed with a decay time of 48 ms, representing one of the highest detectivity values reported for ε ‐Ga 2 O 3 ‐based SBPDs. Due to the introduction of the low‐temperature buffer layer, the quality of the epilayer has been improved, the leakage channel of the epilayer is compensated, and the dark current is reduced. Additionally, a device with a bilayer structure has two paths for carrier transport under illumination, which greatly increases the photocurrent. Furthermore, as a proof‐of‐concept application, a 5 × 5 photodetector array using Ge‐doped ε ‐Ga 2 O 3 epitaxial wafers successfully captured clear images. This work provides a feasible strategy for developing ε ‐Ga 2 O 3 SBPDs with high sensitivity and rapid response characteristics.