High and broadband sensitivity front-side illuminated InGaAs photo field-effect transistors (photoFETs) with SWIR transparent conductive oxide (TCO) gate

By using a transparent conductive oxide (TCO) gate for the short-wave infrared (SWIR) region, the high optical responsivity of 180 A/W at 1550 nm and the broadband photosensitivity up to 1800 nm are demonstrated in InGaAs photo field-effect transistors (photoFETs) with front-side illumination (FSI). The photoresponse of the InGaAs photoFETs through the TCO gate can be reasonably explained by the photovoltaic effect in the photoFET operation. It was found that the spectral responsivity characteristics of TCO gate InGaAs photoFETs exhibit higher and broader responsivity compared with those of the InGaAs photodiode. The TCO gate InGaAs photoFETs are the most promising architecture for a high responsivity and broadband SWIR FSI photodetector for monolithic integration with optical communication devices and Si-LSI.