Search

Abstract: In this work, 0.30μm thick LiNbO3 layers have been deposited by sputtering on nanocrystalline diamond/Si and platinised Si substrates. The films were then analyzed in terms of their structural and optical properties. Crystalline orientations along the (012), (104) and (110) axes have been detected after thermal treatment at 500°C in air. The films were near-stoichiometric and did not reveal strong losses or diffusion in lithium during deposition or after thermal annealing. Pronounced decrease of the roughness on top of the LiNbO3 layer and at the interface between LiNbO3 and diamond was also observed after annealing, compared to the bare nanocrystalline diamond on Si substrate. Furthermore, ellipsometry analysis showed a better density and a reduced thickness of the surface layer after post-deposition annealing. The dielectric constant and losses have been measured to 50 and less than 3.5%, respectively, for metal/insulator/metal structures with 0.30μm thick LiNbO3 layer. The piezoelectric coefficient d 33 was found to be 7.1pm/V. Finally, we succeeded in switching local domain under various positive and negative voltages. [Copyright &y& Elsevier]

Electrical and structural properties of metal-oxide-semiconductor capacitors having as dielectric nanoscopic LaAlO3 or HfAlOx. films deposited on nitrided or nonnitrided Si substrates were investigated. The electrical superiority of RuO2/HfAlOx/SiON/Si stacks was evidenced by a dielectric Constant of 19 and a leakage current density of 67 mA/cm2 at a gate voltage of - 1 V, for a capacitance equivalent to silicon oxide thickness of 1.1 nm. Morphology, composition, and structure of the stacks were accessed by X-ray diffraction and refiectometry, spectroscopic ellipsometry, X-ray photoelectron spectroscopy, and narrow resonant nuclear reaction profiling with isotopic substitution. In spite of presenting crystalline phases associated with HfO2, the HfAlOx. dielectric layers led to a smoother and thinner interfacial layer, improved by the thermal nitridation of the Si substrate prior to high-K deposition. This SiON-like interlayer thickness is self-limited even after postdeposition annealing owing to the formation of an effective diffusion barrier by the strong N-Si-N and N-Si-O-N bonds, which is also effective in preventing substrate oxidation. [ABSTRACT FROM AUTHOR]

Abstract: In order to investigate the effects of the sputter deposition parameters and the influence of the post-deposition thermal treatment on the LaAlO3/Si interface, Rutherford Backscattering Spectrometry (RBS), ion channeling, Nuclear Reaction Analysis (NRA), X-ray Photoemission Spectroscopy (XPS), Capacitance–Voltage measurements and Spectroscopic Ellipsometry (SE) were performed on LaAlO3/Si or RuO2/LaAlO3/Si Metal-Oxide-Semiconductor (MOS) structures. RBS-channeling revealed that the Si surface damage due to sputtering deposition at LaAlO3/Si interface is reduced when increasing the deposition pressure, between 0.5 and 5 Pa, and when annealing the films in 1 atm of O2 at 450 °C. XPS spectra were correlated to RBS and NRA measurements. Even if the formation of a low-κ interfacial layer is demonstrated by SE measurements, high deposition pressure and post-deposition annealing in O2 at 600 °C were found to be the best procedure to improve the electrical characteristics of MOS structures in terms of fixed charge and slow trap densities. For these parameters, the κ value was found to be 14, and the equivalent interfacial thickness was estimated to be 1.3 nm, which is lower that most of the previously reported values. [Copyright &y& Elsevier]

The influence of processing parameters on the electrical characteristics of RuO2/LaAlO3/Si metal-oxide-semiconductor structures was investigated. In particular, the sputtering regime during deposition of LaAlO3 on Si and the atmosphere used in the post-deposition annealing step were addressed by determining capacitance-voltage and gate current-voltage characteristics. These results were correlated with compositional information obtained by Rutherford backscattering spectrometry and nuclear reaction analysis. A post-deposition annealing step in oxygen at 600 °C resulted in better electrical characteristics of the final structure as compared to the same treatment performed in nitrogen. This result is explained by oxygen ability to heal oxygen vacancies in the LaAlO3 film, especially at the dielectric/semiconductor interface region. A thermalized sputtering regime during deposition of LaAlO3 on Si leads to capacitors with electrical characteristics superior to those deposited in ballistic regime. [ABSTRACT FROM AUTHOR]

Abstract: La and Hf aluminates are promising candidates to replace SiO2 as gate dielectric for future Si-based metal–oxide–semiconductor devices. In this study, ion beam analyses were employed to investigate the composition of La and Hf aluminate thin films deposited on Si and the modifications caused in these structures by annealing in low-pressure oxygen atmosphere. Complementary analyses were performed by electrical characterization of metal–oxides–semiconductor capacitors. Results are discussed in terms of oxygen diffusion, substrate Si oxidation and healing of O-deficient sites during annealing in O2. [Copyright &y& Elsevier]