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Solid source molecular beam epitaxy is used to explore the growth of carbon films directly on Si(111). It is shown that graphitic carbon is grown by the implementation of a thin amorphous carbon film that suppresses the formation of SiC precipitates. Raman scattering measurements show the D and G vibrational phonon modes, indicating graphitic ordering in the carbon film. X-ray photoelectron spectroscopy is used to verify the formation of sp2 bonds in the graphitic carbon films and confirms the suppression of SiC.

HfO 2 thin films have been deposited by an atomic layer deposition (ALD) process using alternating pulses of tetrakis-ethylmethylamino hafnium and H2O precursors at 250 °C. The as-deposited films are mainly amorphous and nearly stoichiometric HfO2 (O/Hf ratio ∼1.9) with low bonded carbon content (∼3 at. %). A comparison of the nucleation stage of the films on OH- and H-terminated Si(100) surfaces has been performed using Rutherford backscattering spectrometry, x-ray photoelectron spectroscopy (XPS), and spectroscopic ellipsometry (SE). We find for the initial 5–7 process cycles that the film nucleates more efficiently on the OH-terminated surface. However, after the 7th cycle both surfaces exhibit similar surface coverage, which takes about 40 cycles to reach a steady growth rate per cycle. Angle resolved XPS measurements reveal the formation of a ∼6 Å interfacial layer after four ALD cycles on the H-terminated surface and the thickness of the interfacial layer does not change substantially between the 4th and the 50th process cycles as shown by transmission electron microscopy. Although the surface coverage is comparable for both starting surfaces, film measurements performed by SE suggest that thick films deposited on H-terminated Si are ∼5% thicker than similar films on the chemical oxide surface. Atomic force microscopy (AFM) measurements reveal higher surface roughness for the films deposited in the H-terminated surface. The SE and the AFM data are consistent with higher porosity for the films on H-terminated surfaces.

Compositionally layered BaxSr1−xTiO3 (Ba0.60Sr0.40TiO3–Ba0.75Sr0.25TiO3–Ba0.90Sr0.10TiO3) 220nm thin film heterostructures were fabricated on Pt coated high resistivity Si substrates via the metal organic solution deposition technique (MOSD). Optimization of the material design was achieved by evaluating two integration schemes, namely, the single- and multianneal process protocols. Materials characterization demonstrated that both film process protocols resulted in smooth, dense, crack-free films with a single phase perovskite structure. Rutherford backscattering spectroscopy revealed compositionally distinct layers and severe elemental interdiffusion for the films fabricated via the multianneal and single-anneal process protocols, respectively. The retention of the compositional layering subsequent to film crystallization deemed the multianneal processed BaxSr1−xTiO3 (BST) film suitable for evaluation of dielectric properties. The dielectric properties were compared to both paraelectric uniform composition BST and to the relevant compositionally graded BST films reported in the technical literature. Our results made evident that the multiannealed compositionally layered BST films possessed higher permittivity (εr=360) and lower dissipation factor (tanδ=0.012) with respect to both uniform composition paraelectric Ba0.60Sr0.40TiO3 film fabricated via the same MOSD processing method and the relevant literature values for compositionally graded BST films. The multilayered BST material design exhibited minimal dielectric dispersion in the range of 90to−10°C, showing a 6.4% decrease in permittivity (corresponding to a temperature coefficient of capacitance TCC20–90=−0.921) as the temperature was elevated from 20to90°C and only a 2.1 increase in permittivity (TCC20–(−10)=−0.716) as the temperature was lowered from 20to−10°C. Additionally, the dielectric tunability of the multilayered BST structures over the temperature range of −10–90°C was temperature independent. Our results show that the multilayered BST design has excellent dielectric properties and the enhanced tunability and dielectric loss are stable over a relatively broad temperature range (−10–90°C), thereby making them excellent candidates for the next generation of enhanced performance temperature stable tunable devices.