CHARACTERIZATION OF MOVPE-GROWN ALGAAS/GAAS SINGLE QUANTUM WELLS BY INTERSUBBAND INFRARED-ABSORPTION

Intersubband infrared absorption in the conduction band of AlGaAs/GaAs quantum wells is presented as a characterization technique for evaluating quantum well width provided that the aluminum content is independently measured by other techniques. An analysis of the sensitivity of the intersubband wavenumber as a function of QW width and height (e.g. aluminum content in the barrier layers) is done, which results in ca. 30 cm-1 change in wavenumber/monolayer (0.28 nm) and ca. 15 cm-1 change/% change in aluminum content x (calculated at width 8 nm and x=0.25). Numerical simulation shows that the influence of graded interfaces, many-body effects in the free electron plasma, dynamic plasma interaction with the electromagnetic radiation, and band-bending in the AlGaAs layers is minor, at least for sheet free carrier concentrations up to 1×1012 cm-2.