InAs/GaAs self-organized quantum dot far-infrared detectors

Abstract

Summary form only given. Heterostructures consisting of doped InAs self-organized quantum dot structures were grown by molecular beam epitaxy for far-infrared measurements. Photoluminescence (PL) measurements reveal the spectral position of the band-to-band transitions of the InAs quantum dot ground state and bulk GaAs, with a peak intensity energy separation of /spl sim/4-5 /spl mu/m, which corresponds to the shortest wavelength where bound state transitions should be expected. Far-infrared transmission measurements were made on similar structures with a FTIR spectrometer. Far-infrared absorption is observed in the range of 6-16 /spl mu/m for samples with doped InAs quantum dots, with no comparative absorption for undoped samples where there are no free carriers for absorption. Far-infrared photoconductivity measurements were made using a low noise current amplifier and a FTIR spectrometer. Measurements at 90 K under normal incidence reveal a photoconductivity response in the range of 10-21 /spl mu/m, which is not observed in the absence of illumination. The observed response is likely due to intersubband transitions in the quantum dots through comparison to the PL spectra.