High-speed photodetectors for the 950–1100 nm optical range based on In$_{0.4}$Ga$_{0.6}$As/GaAs quantum well-dot nanostructures

High-speed photodetectors (PDs) based on InGaAs/GaAs quantum well-dot (QWD) nanostructures with the frontal-end and back-end input of radiation have been studied. A PD with 40 rows of QWDs exhibited a spectral responsivity of up to 0.4 A/W in the 950–1100 nm optical range at a –5-V bias voltage. The decay time constant of pulsed response for PDs with an input area of 1.4 $\times$ 10$^{-4}$ cm$^2$ was $\sim$250 ps.