Thickness evaluation of InGaAs/InAlAs quantum wells

This work proposes a new optoelectronic measurement of quantum well (QW) thickness and applies it to doped and undoped In0.53Ga0.47As/In0.52Al0.48As multiple-QW structures. Near-infrared spectroscopic identification of the interband optical transition at 100-300 K gave the eigenenergies of the conduction band in the QW. Evaluation of the QW thickness involved analysis of the effective mass at the corresponding eigenenergy. QW thicknesses in the range of 5.45-20.8 nm were determined in six different wafers. These thicknesses agreed well with the QW thicknesses estimated by double-crystal x-ray diffraction within almost two monolayers. This measurement was used to determine the distance of potential boundaries confining the electron wave functions.