Composition dependence of band offsets for (LaAlO_3)_(1-x)(Al_2O_3)_x gate dielectrics determined by photoelectron spectroscopy and x-ray absorption spectroscopy

摘要

Electronic structures of (LaAlO_3)_(1-x)(Al_2O_3)_x composite films (x = 0, 0.2, 0.33, 0.5, and 1) for large scale integration (LSI) gate dielectrics deposited on p-type Si (100) substrates by a combinatorial pulsed laser deposition method have been analyzed using photoelectron spectroscopy and x-ray absorption spectroscopy. The systematic peak shifts due to chemical shifts were observed for core-level spectra. The conduction-band offset became smaller with increasing ratio of Al_2O_3, while the valence-band offset became larger. This precise determination of the band diagram revealed that LaAlO_3 (x = 0) had the optimum band offset for LSI gate dielectrics.