ABSTRACT
We present experimental data on the photoresponse in heterodimensional optoelectronic FETs (2D-MESFETs). The photoresponse in a 2-D MESFET is higher than that of the P-HEMT under top-illumination, since the P-HEMTs top gate blocks incoming light and reduces photosensitivity. The 2-D MESFET responds to the electromagnetic radiation in a wide spectral range, since the electron-hole pairs may be generated in the GaAs substrate, in the InGaAs quantum well, and in the AlGaAs layer. These photoresponse mechanisms include photoconductive effect (an increase in the channel conductivity caused by the electron-hole pair generation), electron-hole pair separation by the electric field in the gate depletion regions, a related photovoltaic effect of inducing the gate bias by the optical signal, and a shift in the threshold voltage (and related gain).
