Large-area nanogap plasmon resonator arrays for plasmonics applications

Large-area (∼8000 mm(2)) Au nanogap plasmon resonator array substrates manufactured using maskless laser interference lithography (LIL) with high uniformity are presented. The periodically spaced subwavelength nanogap arrays are formed between adjacent nanopyramid (NPy) structures with precisely defined pitch and high length density (∼1 km cm(-2)), and are ideally suited as scattering sites for surface enhanced Raman scattering (SERS), as well as refractive index sensing. The two-dimensional grid arrangement of NPy structures renders the excitation of the plasmon resonators minimally dependent on the incident polarization. The SERS average enhancement factor (AEF) has been characterized using over 30 000 individual measurements of benzenethiol (BT) chemisorbed on the Au NPy surfaces. From the 1(a(1)), β(CCC) + ν(CS) ring mode (1074 cm(-1)) of BT on surfaces with pitch λ(g) = 200 nm, AEF = 0.8 × 10(6) and for surfaces with λ(g) = 500 nm, AEF = 0.3 × 10(7) from over 99% of the imaged spots. Maximum AEFs > 10(8) have been measured in both cases.