Nguyen Hoang Long, Bao Le Huu, Le Tran
Vietnam National University Ho Chi Minh City Ho Chi Minh City 70000 Vietnam
Faculty of Physics & Engineering Physics, VNUHCM-University of Science Ho Chi Minh City 70000 Vietnam.
RSC Adv. 2025 May 23;15(22):17365-17376. doi: 10.1039/d5ra02866c. eCollection 2025 May 21.
This study investigates the structural, electrical, and optical properties of NiO thin films deposited by DC sputtering in an Ar/O atmosphere with varying oxygen concentrations. As the O content increases, energy-dispersive X-ray (EDX) analysis reveals a higher concentration of Ni vacancies and Ni ions, resulting in lower resistivity and a slight reduction in crystal quality. Among the samples, the film grown at 50% oxygen (NiO-50) exhibits the best combination of properties for Surface-Enhanced Raman Spectroscopy (SERS), including balanced crystallinity, surface roughness, and high hole concentration. Current-voltage (-) measurements and Raman spectra using Rhodamine 6G (10 M) confirm that the SERS enhancement is driven by an electron transition mechanism. The calculated enhancement factor of 9.6 × 10 for the NiO/Si substrate surpasses previously reported values. These results position NiO-50 as a promising SERS-active material and provide insights into tuning NiO film properties for enhanced sensing applications.
本研究调查了在不同氧气浓度的氩气/氧气气氛中通过直流溅射沉积的NiO薄膜的结构、电学和光学性质。随着氧含量的增加，能量色散X射线（EDX）分析显示Ni空位和Ni离子的浓度更高，导致电阻率降低和晶体质量略有下降。在这些样品中，在50%氧气（NiO-50）下生长的薄膜表现出用于表面增强拉曼光谱（SERS）的最佳性能组合，包括平衡的结晶度、表面粗糙度和高空穴浓度。使用罗丹明6G（10 M）的电流-电压（I-V）测量和拉曼光谱证实，SERS增强是由电子跃迁机制驱动的。NiO/Si衬底的计算增强因子为9.6×10，超过了先前报道的值。这些结果使NiO-50成为一种有前途的SERS活性材料，并为调整NiO薄膜性能以增强传感应用提供了见解。
