Optical Sensing Characteristics in a Transparent Al-Doped Zinc Oxide-Gated Al0.2Ga0.8As/In0.2Ga0.8As High Electron Mobility Transistor

A three-terminal optical sensor by using an aluminum-doped zinc oxide (AZO)-gated Al_0.2Ga_0.8As/In_0.2Ga_0.8As high electron mobility transistor (AZO-HEMT) on a GaAs substrate is demonstrated in this report. Optical responses under illumination of different wavelengths are investigated, as compared to a conventional Au-gated HEMT device. Experimental results demonstrate that the present design is promising for tunable optical sensing applications.