Enhancing Detection Sensitivity of ZnO-Based Infrared Plasmonic Sensors Using Capped Dielectric GaO Layers for Real-Time Monitoring of Biological Interactions.

Surface plasmon resonances on Ga-doped ZnO (ZnO/Ga) layer surfaces (ZnO-SPRs) have attracted substantial attention as alternative plasmonic materials in the infrared range. We present further enhancement of the detection limits of ZnO-SPRs to monitor biological interactions by introducing thin dielectric layers into ZnO-SPRs, which remarkably modify the electric fields and the corresponding decay lengths on the sensing surfaces. The presence of a high-permittivity dielectric layer of GaO provides high wavelength sensitivities of the ZnO-SPRs due to the strongly confined electric fields.