High photoconductive gain in GexSi1−x/Si strained-layer superlattice detectors operating at λ=1.3 μm

We demonstrate high photoconductive gain in GexSi1−x/Si strained-layer superlattice detectors grown by molecular beam epitaxy. The gain mechanism is considered to be the preferential hole trapping in the GexSi1−x wells. Ge0.6Si0.4 waveguide devices operating at the wavelength of 1.3 μm show an optical gain as large as 40 at a low bias of 5–7 V and a gain bandwidth product as large as 3.6 GHz. Preliminary bit error experiments show sensitivity sufficient for transmission at distances of over 25 km and data rates of 200 Mb/s.