Optical properties of quantum dot infrared photodetector with dot in an asymmetric well structure

We have investigated the device characteristics of quantum dot infrared phto detector (QDIP) utilizing InAs QDs in an In_0.15Ga _0.85As quantum well structure. Device characteristics, such as dark current, photoluminescence (PL), and photocurrent spectra, have been measured. Two peak positions were measured at 163 and 219 meV in photocurrent spectrum. The photo-current of the peak at 163 meV was larger than that at 219 meV. The full width at half maximum (FWHM) of the peak at 163 meV was 18 meV, which was attributed to bound-to-bound transition. In_0.15Ga_0.85As layers were believed to contribute to induce bound-to-bound transition energy (163 meV). The activation energies of electrons in an InGaAs QDs were determined to be 171 meV and 221 meV from temperature-dependent integrated PL intensities. These activation energies from PL measurement are quite well matched to peak IR detection energies of 163 meV and 219 meV from the photo-current spectrum. This result implies that one can estimate the peak IR detection wavelength of QDIP from PL measurements of QDIP structure before its fabrication and measurement.