Photoconductivity in lateral conduction self-assembled Ge/Si quantum dot infrared photodetectors

摘要

We have investigated the photocurrent spectra of lateral conduction self-assembled Ge/Si quantum dots (QDs) infrared photodetector structure. We have observed a broad mid-infrared photocurrent spectrum in photon energy range of 120-400 meV (λ～3-10 μm) due to bound-to-bound as well as bound-to-continuum intersubband transition of normal incidence radiation in the valence band of self-assembled Ge QDs and subsequent lateral transport of photoexcited carriers in the Si/SiGe two-dimensional channel. The peak responsivity was as high as 134 mA/W at photon energy of 240 meV (λ～5.2 μm) at T=10 K and V_b=8 V. Furthermore, the electronic states in valence band of Ge QD were clarified by using several optical measurements.