XPS analysis and electrical conduction mechanisms of atomic layer deposition grown Ta₂O₅ thin films onto p-Si substrates Available to Purchase

Metal oxide semiconductor capacitors that incorporate tantalum pentoxide (Ta₂O₅) thin films as dielectric were fabricated via the atomic layer deposition (ALD) technique and characterized through TEM, XPS, C–V, and I–V measurements. TEM analysis revealed the amorphous phase of Ta₂O₅ films and the existence of an ultrathin SiO_x layer in the Ta₂O₅/p-Si interface, also evidenced by XPS spectra. XPS analysis verified the stoichiometry of the ALD-deposited Ta₂O₅ films. Furthermore, XPS results indicate values of 2.5 and 0.7 eV for the conduction and valence band offsets of the Ta₂O₅/p-Si interface, respectively. I–V measurements, for positive and negative applied bias voltages, reveal that the conduction is governed by Ohmic, trap controlled space charge limited, and Schottky mechanisms depending on the applied voltage and temperature region. Through the analysis of Schottky emission data, the conduction band offset of Ta₂O₅/p-Si (φ_Β) is calculated to be 0.6 eV, while the valence band offset is 2.6 eV, in very good agreement with the XPS results. The energy band diagram of Ta₂O₅/p-Si is constructed.