Photocurrent spectroscopy of indirect transitions in Ge/Si multilayer quantum dots at room temperature

Lateral photoconductivity spectra of multilayer Ge/Si heterostructures with Ge quantum dots were studied in the work proposed at room temperature. The photocurrent with minimal energy 0.48-0.56 eV that is smaller than Ge band gap was observed from such structures at the geometry of waveguide excitation. Generation of the photocurrent with the limit energy 0.48-0.56 eV was explained by spatially indirect electron transitions from heavy hole states of SiGe valence band into Δ2-valley of the conduction band of Si surrounding. It was found out that the limit energy of such transitions decreased, as the number of SiGe quantum dot layers increased.