Optically tunable feedback operation of silicon nanowire transistors

In this study, we present an optically tunable feedback field-effect transistor (FBFET) with two independent gates and a p ⁺ -i-n ⁺ silicon nanowire. Because of the feedback operation, the FBFET features extremely steep switching characteristics with subthreshold swings <4 mV dec^-1, and it can be reconfigured as a p- or n-type transistor by controlling the gate-voltage biases. When the FBFET is exposed to a He-Ne laser beam (λ = 633 nm), photogenerated carriers accumulate in the potential wells and reduce the potential-barrier height. The optically tunable feedback operation is attributed to the lowering of the potential barrier caused by the light. The triggering voltages can be modulated according to illumination, even when feedback is being provided. This optically tunable transistor with excellent switching characteristics opens up possibilities for application in future optoelectronic devices.