Graphene-Coupled Highly Efficient THz Photomixer

A novel THz photomixer detector based on interdigitated multilayer graphene (MLG) on low-temperature-grown (LTG) GaAs is demonstrated. It exhibits an enhanced performance as compared with conventional LTG GaAs photomixers with metallic finger contacts. The obtained responsivity and the dynamic range are about 30x higher and the bandwidth is twice as large. The reason for this enormous improvement lies in the transparency of the graphene electrodes to VIS/NIR radiation which permits to optically excite mobile charge carriers in the LTG GaAs not only between the electrode fingers, but also below them. The measured enhancement of the detected photocurrent is explained by model calculations and simulations.

Automated summary

A novel THz photomixer detector based on interdigitated multilayer graphene on low-temperature-grown GaAs is demonstrated, showing enhanced performance compared to conventional GaAs photomixers with metallic finger contacts. The improvement is explained by the transparency of the graphene electrodes to VIS/NIR radiation, allowing optical excitation of charge carriers not only between, but also below the electrode fingers. Model calculations and simulations were used to explain the enhanced detected photocurrent.