Novel photovoltaic transistor directly modulated by steady-state photovoltage in asymmetric superlattices

The authors demonstrate the realization of a novel photovoltaic transistor. The channel conductivity of the transistor is directly controlled by a photovoltage generated in an asymmetrical semiconductor superlattice. The photovoltage and thus the modulation on the transistor respond linearly to the intensity of the incident light at low intensities, and saturate at a level at high intensities. The saturation level is determined by the majority carrier mobility and the minority carrier lifetime in the superlattice. It can be tailored at the preparation of the superlattice. The photovoltaic transistor has a large bandwidth. Its ultimate speed is on the order of picoseconds. Compared to conventional photoconductive detectors, the novel photovoltaic transistor shows particular advantages for optoelectronic integration.<>