Silicon-on-insulator and SiGe waveguide photodetectors with Ge/Si self-assembled islands

Abstract

We have investigated near infrared p–i–n waveguide photodetectors with Ge/Si self-assembled islands as optical active region. Two samples with Ge islands grown by high-pressure chemical vapor deposition were studied. The first sample consists of a p–i–n junction with islands embedded in a silicon-on-insulator waveguide. The second sample consists of a p–i–n junction with Ge island layers embedded in a Si 0.98Ge 0.02 alloy waveguide. The spectral responsivity of the detectors was measured with a broad-band source and with semiconductor laser diodes. At room temperature both samples exhibit similar responsivities at 0 V applied bias, with 55 (25) mA/ W at 1.3 μm and 0.15 (0.25) mA/ W at 1.55 μm for the Si 0.98Ge 0.02 alloy (silicon-on-insulator) waveguide. The photocurrent results are correlated to the interband absorption and to the photoluminescence of the islands.