Self-consistent determination of the band offsets in InAsxP1-x/InP strained-layer quantum wells and the bowing parameter of bulk InAsxP1-x

Low- and room-temperature optical absorption spectra are presented for a series of InAsxP1-x/InP strained-layer multiple quantum well structures (0.11 less than or equal to x less than or equal to 0.35) grown by low-pressure metal-organic vapor phase epitaxy using trimethylindium, tertiarybutylarsine, and phosphine as precursors. The well widths and compositions in these structures are exactly determined from the use of both high-resolution x-ray diffraction and transmission electron microscopy on the same samples. The absorption spectra are then analyzed by self-consistently fitting, for the five samples, the excitonic peak energy positions with transition energies determined from a solution to the Schrodinger equation in the envelope function formalism using the well-known Bastard/Marzin model [J. Y. Martin et al., in Semiconductors and Semimetals, edited by Thomas P. Pearsall, (Academic, New York, 1990), Vol. 32, p. 56]. From these self-consistent fits, both the bowing parameter of bulk unstrained InAsxP1-x and the band offsets of the heterostructures are deduced self-consistently. The conduction-band offsets thus determined represent 75%+/-3% of the total strained band-gap differences at both low (liquid He) and room temperatures. These values of the band offsets are consistent with the predictions of the quantum dipole model [J. Tersoff, Phys. Rev. B 30, 4874 (1984)]. The values determined for the bowing parameters are found to differ slightly between 0.10+/-0.01 eV at low temperature and 0.12+/-0.01 eV at room temperature.