An InAlAs-InGaAs OPFET with responsivity above 200 A/W at 1.3-μm wavelength

The optoelectronic dc and RF behaviour of an InAlAs-InGaAs optically controlled field-effect transistor based on a high electron mobility transistor layer structure is investigated at 1.3-/spl mu/m wavelength light. The device is backside-illuminated to increase the responsivity. A transistor with 0.3-/spl mu/m gate length and an active area of 50/spl times/50 /spl mu/m/sup 2/ exhibits a responsivity of 235 A/W, at 11-/spl mu/W incident optical power. The photoconductive response is higher than for an metal-semiconductor-metal photodetector with the same InGaAs absorption layer thickness up to 10 GHz.