Realization of a photovoltaic transistor based on a steady-state internal polarization effect in asymmetric semiconductor superlattices

Abstract

We have used molecular beam epitaxy to grow at 500 °C a graded InAlGaAs superlattice structure sandwiched by two heavily doped window layers which are directly connected to the gate and source of a discrete field-effect transistor (FET). Upon band-gap illumination, a steady-state photovoltage controllable by the light intensity is generated by the superlattice structure, which then modulates the drain current of the FET to the same amount as does a dc voltage source. The intrinsic response time of the photovoltaic effect is on the order of picoseconds, thus the modulation speed on the drain current is completely limited by the FET.