Response spectra from mid- to far-infrared, polarization behaviors, and effects of electron numbers in quantum-dot photodetectors

Photoresponse characteristics of InAs/GaAs self-assembled quantum-dot infrared photodetectors in a wide spectral region from the mid- to far-infrared are reported. Clear polarization behaviors with a dominant P-polarized response in the mid-infrared and a strong S-response in the far infrared are shown. These behaviors can be qualitatively understood in view of the quantum-dot shape of a large in-plane diameter and a small height in the growth direction. With a set of three samples, effects of the number of electrons per dot on the spectra are investigated.