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Highlights: [•] Al2O3/HfO2/Al2O3 gate stacks has been deposited on Si substrate by ALD. [•] Interface thermal stability related with annealing temperature has been studied. [•] Phase separation at 700°C and silicate formation at 900°C have been detected. [ABSTRACT FROM AUTHOR]

In current work, effects of rapid thermal annealing on the interface chemical bonding states, band alignment, and electrical properties of atomic-layer-deposition-derived HfAlO/Al 2 O 3 gate stack on Si substrates have been studied by X-ray photoemission spectroscopy (XPS), UV–Vis transmission spectroscopy, and electrical measurements. XPS analyses have shown that HfAlO alloy and mixed silicate (Hf-Al-O-Si) increase after post-deposition annealing process. By means of UV–Vis transmission spectroscopy measurements, reduction in band gap for 400 o C-annealed sample has been observed. Accordingly, reduction in the valence band offset and increase in the conduction band offset have been detected for HfAlO/Al 2 O 3 /Si gate stack annealed at 400 °C. Various current conduction mechanisms, such as Poole-Frenkel emission, Fowler-Nordheim (FN) tunneling, and space-charge-limited (SCL) conduction, have been analyzed. Detailed electrical measurements reveal that current conduct mechanisms is SCL conduction at lower field region and FN tunneling and SCL conduction are dominant conduction mechanism at higher field region. [ABSTRACT FROM AUTHOR]

Interfacial thermal stability and band alignment of ALD-derived Al 2 O 3 /HfO 2 /Al 2 O 3 /Ge gate stacks have been investigated by X-ray photoelectron spectroscopy (XPS) and spectroscopy ellipsometry (SE) as a function of annealing temperature. It has been found that reduction in interfacial GeO x component and formation of HfAlO alloy layer have been detected with increasing the annealing temperature from 500 to 700 °C. Combined with analysis from XPS and SE, the increase in conduction band offset and reductions in band gap and valence band offset have been observed. When annealing temperature reaches 700 °C, the valence band offset has been reduced to 0.88 eV, which is smaller than the minimal requirement of Δ E v values for high- k dielectrics and, thus, leads to unacceptably high leakage currents. Therefore, annealing temperature should be carefully controlled to guarantee excellent properties of Al 2 O 3 /HfO 2 /Al 2 O 3 /Ge gate stacks in future Ge-based MOS devices. [ABSTRACT FROM AUTHOR]

The change of phonon energies of annealed InGaAs/GaAs quantum dots (QDs), was observed using selectively excited photoluminescence. X-ray diffraction and optical anisotropy analysis shows that the QDs’ structure mainly changes along the growth direction. [Copyright &y& Elsevier]