Performance enhancement of MOCVD grown Zn-doped β-Ga₂O₃ Deep-Ultraviolet photodetectors on silicon substrates via TiN buffer layers

Integrating β-Ga₂O₃-based devices on silicon substrates faces challenges due to lattice and thermal expansion mismatches, leading to performance-degrading defects. Therefore, this work explores the utilization of a titanium nitride (TiN) buffer layer in order to enhance the performance of MOCVD grown Zn-doped β-Ga₂O₃-based deep-ultraviolet (DUV) photodetectors (PDs) on silicon substrates with 12, 24, and 36 sccm diethylzinc (DEZn) flow rates. The XPS depth profiles revealed the presence of TiN buffer layer in β-Ga₂O₃/TiN/Si films, which served as a diffusion barrier during deposition, preserving interface integrity and reducing defect density. Zn-doped β-Ga₂O₃/TiN/Si based DUV PDs revealed remarkable results. The 12 sccm Zn-doped β-Ga₂O₃/TiN/Si PDs demonstrated an exceptional maximum responsivity of 31.4 A/W, which is 7 times higher compared to the undoped β-Ga₂O₃/TiN/Si (4.47 A/W) under a 5 V bias and 240 nm wavelength illumination. This PD exhibited the detectivity of 1.68 × 10¹³ Jones and EQE of 1.63 × 10⁴ %. This PD possess quick rise time of 6.5 s and fall time of 0.5 s. The energy band diagram for Zn-doped β-Ga₂O₃/TiN/Si metal–semiconductor-metal type PDs is discussed. This work demonstrates that TiN buffer layers and Zn doping significantly improve the performance and reliability of β-Ga₂O₃-based DUV photodetectors on silicon substrates.