Type-II Superlattice Infrared Photodetectors With Graphene Transparent Electrodes

In this letter, we have demonstrated that graphene can act as a transparent electrode on the p-type GaSb substrate. Wavelength-insensitive and over 95% high transmittance are observed for the bi-layer graphene in the infrared light range. By using graphene as the transparent electrode, over ten-time responsivity enhancement is observed for the InAs/GaSb type-II superlattice infrared photodetector. The phenomenon is attributed to the shortened carrier transport paths resulted from the vertical current flow to the graphene electrode. The results have revealed the potential of graphene for the application of infrared transparent electrodes.