Influence of Nitrogen Implantation on Electrical Properties of Al/SiO2/4H-SiC MOS Structure

In this article, an influence of nitrogen implantation dosage on SiC MOS structure is analyzed using wide range of nitrogen implantation dose (between ~1013 – 1016). Authors analyzed electrical and material properties of investigated samples using C-V, I-V measurements, Raman spectroscopy, and XPS profiling. It has been shown that surface state trap density is directly connected to implantation damage and thus implantation conditions. Using research results a trap origin at given energy can be concluded.

The Magnetic Ordering of SiCN Films Prepared by Ion Implantation

Room-temperature ferromagnetism was observed in the SiCN films prepared by ion implantation. The result indicates that N ion implantation dosage in the film has great effect on the observed room-temperature ferromagnetism of the films. Along with the increase of ion implantation dosage, the N ions increase and the magnetism enhances. Because of the ion implantation will cause a lot of defects on the surface of SiC films, which will induce a lot of vacancies. The C atoms are replaced by the N ions doped, the concentration of the N ions decides the charges states and spin polarizations of Si vacancy defects. Local magnetic moment is induced because of the spin polarization of the Si vacancy defects, and the films show ferromagnetic properties.Charge states and spin polarizations of silicon vacancy defects can be manipulated by N atoms which induces the ferromagnetism.

Effects of MeV Ions on Thermal Stability of Single Walled Carbon Nanotubes

The properties of carbon nanotubes (CNTs) are closely dependent on their structures, and therefore may be tailored by controllably introducing defects in the nanotube systems. In this work, we have investigated the effects of energetic ions (H+ and He+) on the thermal stability of single wall nanotubes (SWNTs) against oxidation in air. SWNTs were irradiated with MeV ions to various doses in the range 1013-1016 cm−2. Thermogravimetric analysis (TGA) was used to determine the loss of CNT masses as a result of oxidation processes. As opposed to the case of pristine SWNTs for which the temperature (Tmax) corresponding to maximum oxidation rate was found to be ∼ 495 °C, ion beam processing significantly enhanced the thermal stability of nanotubes, e.g., Tmax increased by about 30 °C after H+ implantation (dosage: 1015 cm−2) and 17 °C after He+ implantation (dosage: 1013 cm−2). The activation energies for thermal oxidation under various conditions were also extracted from TGA data, with values ranging from 1.13 eV (for pristine SWNTs) to 1.37 eV, depending on ion doses and species. Raman spectroscopy was used to determine the characteristics of the G band (C-C stretching mode) and D band (disorder induced mode) in CNTs. The work suggests that the SWNTs modifies to more stable structure (may be cross-linked SWNTs) at small doses. Once the number of defects exceeds some critical value (depending on the type and dosage of bombarding ion) the bonding energy in CNTs weakens, leading to the reduced thermal stability of CNTs against oxidation.

Ion-Implantation of Reactive Elements in Improving the Adhesion of Thermally Grown Cr2O3 Sales

The high temperature oxidation behavior of Al, Y and Hf ion-implantation in Ni-25wtCr alloy with dosages ranging from 1015-1017 ions/cm2 has been studied. Results are compared with the unimplanted alloy, a Xe-implanted alloy and alloys with 0.2wt% Y or lwt% Al additions. Oxidation tests were carried out at 1000°C and 1100°C in 1 atm. O2. It is found that the ion-implantation of Y and Hf greatly reduced oxidation rate and improved scale adherence after a critical implantation dosage, ∼ l×1016 ions/cm2, has been reached. The improved scale adhesion is attributed to both a reduction in growth stress and a strengthened scale/alloy interface, which all developed as a result of a modified scale growth process.