Midinfrared Photoconductivity in Ge/Si Self-Assembled Quantum Dots

Abstract

We have investigated midinfrared photoconductivity of Ge/Si self-assembled quantum dots. The self-assembled quantum dots were grown by ultra-high-vacuum chemical vapor deposition on Si(001). The photoresponse of the p-type device exhibits resonances in the midinfrared around 10 μm wavelength. The photocurrent resonances are associated with intraband transitions in the valence band of the quantum dots. The photocurrent is studied as a function of applied bias and of the polarization of the incoming light. Bound-to-bound and bound-to-continuum transitions are shown to contribute to the photocurrent. The photocurrent peaks are correlated with the photoluminescence of the device.