TCO/metal hybrid structures for surface plasmon enhanced light emitting in the near infrared range (Presentation Recording)

Transparent conductive oxides (TCOs, such as Sn:In2O3, Al:ZnO, Ga: ZnO et al) have re-drawn people’s attention as alternative candidates of noble metals (particularly Ag or Au) in the field of plasmonic for the reasons of property tunable and low losses et al. However even for Sn:In2O3 (ITO, reported highest conductivity), the metallic property lies in the near infrared (NIR) range exhibiting the real part permittivity ɛ' was around -3 at communication wavelength of 1.55μm. Under this circumstance, surface plasma polaritons (SPPs) was hard to be exited on the interface between ITO and surrounded dielectric materials with large permittivity. Hence, in order to explore the potential use of TCOs in the applications of silicon photonics (for permittivity of silicon and germanium are 11.6 and 16 at 300K, respectively), we design a hybrid structure of ITO/metal or ITO/metal/ITO as surface plasmonic materials in NIR. The electrical and optical property of hybrid structure was manipulated accordingly by changing the portion of the introduced metal while maintaining a lower loss than bare metals. The highest carrier concentration of the hybrid structure reached 3×10^22cm^-3, definitely the same magnitude of noble metals. Magnetron sputtering and atomic layer deposition (ALD) can be used to deposit the hybrid ITO/metal structure, in which metal represents gold (Au), and iridium (Ir). The normalized radiative decay rate of light emitted by germanium quantum dots reaches a maximum enhancement of ~8-fold with the assistance of ITO/metal hybrid structure according to the finite difference time domain (FDTD) simulation.