Normal-Incidence Far-Infrared Absorption Of Five-Period Inas/Gaas Quantum Dots At Room Temperature

We report a normal-incidence far-infrared absorption above 10 mum of self-assembled InAs quantam dots (QDs) grown by molecular beam epitaxy. The InAs QD layers are embedded in a GaAs matrix with Si delta-doping. The absorption spectrum in the far-infrared range observed at room temperature is attributed to the intersublevel transitions of the InAs QD layer above 10 mum. A Si delta-doped InAs QD sample with a five-period vertically stacked structure shows a photoluminesence spectrum at room temperature, attesting to the high quality of the InAs QDs. This result agrees with the strong normal-incidence far-infrared absorption observed in five-period InAs QD layers with Si delta-doping by using Fourier transform infrared spectroscopy at room temperature.