Improved performance of yttrium-doped Al 2O 3 as inter-poly dielectric for flash-memory applications

Yttrium-doped Al 2O 3Y xAl yO) with different yttrium contents prepared by co-sputtering method is investigated as the inter-poly dielectric (IPD) for flash memory applications. A poor SiO 2-like interlayer formed at the IPD/Si interface is confirmed by X-ray photoelectron spectroscopy, and can be suppressed by Y doping through the transformation of silica into silicate. Compared with Al 2O 3 and Y 2O 3 films, the optimized Y xAl yO film shows lower interface-state density, lower bulk charge-trapping density, higher dielectric constant, and smaller gate leakage, due to the suppressed interlayer and good thermal property ascribed to appropriate Y and Al contents in the film. Therefore, the optimized Y xAl yO film is a promising candidate as the IPD for flash memory. © 2010 IEEE.published_or_final_versio

Nitrided La 2O 3 as charge-trapping layer for nonvolatile memory applications

Charge-trapping characteristics of La 2O 3 with and without nitrogen incorporation were investigated based on Al/Al 2O 3/La 2O 3/SiO 2Si (MONOS) capacitors. The physical properties of the high-k films were analyzed by X-ray diffraction and X-ray photoelectron spectroscopy. Compared with the MONOS capacitor with La 2O 3 as charge-trapping layer, the one with nitrided La 2O 3 showed a larger memory window (4.9 V at ±10-V sweeping voltage), higher program speed (4.9 V at 1-ms +14 V), and smaller charge loss (27% after 10 years), due to the nitrided La 2O 3 film exhibiting less crystallized structure and high trap density induced by nitrogen incorporation, and suppressed leakage by nitrogen passivation. © 2012 IEEE.published_or_final_versio

Improved charge-trapping properties of HfYON film for nonvolatile memory applications in comparison with HfON and Y 2O 3 films

The charge-trapping properties of HfYON film are investigated by using the Al/HfYON/SiO 2/Si structure. The physical features of this film were explored by transmission electron microscopy and x-ray photoelectron spectroscopy. The proposed device shows better charge-trapping characteristics than samples with HfON or Y 2O 3 as the charge-trapping layer due to its higher trapping efficiency, as confirmed by extracting their charge-trap centroid and charge-trap density. Moreover, the Al/Al 2O 3/HfYON/SiO 2/Si structure shows high program speed (4.5 V at 14 V, 1 ms), large memory window (6.0 V at 14 V, 1 s), and good retention property, further demonstrating that HfYON is a promising candidate as the charge-trapping layer for nonvolatile memory applications. © 2011 American Institute of Physics.published_or_final_versio

Charging-induced changes in reverse current-voltage characteristics of Al/Al-Rich Al 2O 3/p-Si Diodes

An Al-rich Al 2O 3 thin film was deposited on a p-type silicon substrate by radio frequency sputtering to form Al/ Al-rich Al 2O 3/p-Si diodes. The current-voltage (I-V) characteristics of the diodes were determined by carrier injection from either the Si substrate or the Al gate and by carrier transport along the tunneling paths formed by Al nanocrystals distributed in the oxide layer. The reverse I-V characteristics were greatly affected by the charge trapping in the oxide layer, i.e., the electron trapping significantly reduced the reverse current while the hole trapping enhanced the current significantly. However, the charge trapping did not produce a large change in the forward I-V characteristic. © 2009 IEEE.published_or_final_versio

Temperature dependence of current transport in Al/Al 2O 3 nanocomposite thin films

In this work, Al/Al 2O 3 nanocomposite thin film is deposited on Si substrate by radio frequency sputtering to form a metal-insulator-semiconductor structure. It is found that the current conduction at low fields is greatly enhanced with temperature. The current increase can be attributed to the decrease in the tunneling resistance and/or the formation of some tunneling paths due to the release of some measurement-induced charges trapped in the thin film as a result of increase in the temperature. The current conduction evolves with a trend toward a three-dimensional transport as the temperature increases. © 2011 American Institute of Physics.published_or_final_versio

LaTiON/LaON as band-engineered charge-trapping layer for nonvolatile memory applications

Charge-trapping characteristics of stacked LaTiON/LaON film were investigated based on Al/Al 2O 3/LaTiON-LaON/SiO 2/Si (band-engineered MONOS) capacitors. The physical properties of the high-k films were analyzed by X-ray diffraction, transmission electron microscopy and X-ray photoelectron spectroscopy. The band profile of this band-engineered MONOS device was characterized by investigating the current-conduction mechanism. By adopting stacked LaTiON/LaON film instead of LaON film as charge-trapping layer, improved electrical properties can be achieved in terms of larger memory window (5.4 V at ±10-V sweeping voltage), higher program speed with lower operating gate voltage (2.1 V at 100-μs +6 V), and smaller charge loss rate at 125 °C, mainly due to the variable tunneling path of charge carriers under program/erase and retention modes (realized by the band-engineered charge-trapping layer), high trap density of LaTiON, and large barrier height at LaTiON/SiO 2 (2.3 eV). © 2012 The Author(s).published_or_final_versionSpringer Open Choice, 28 May 201

CVD of CrO2 Thin Films: Influence of the Deposition Parameters on their Structural and Magnetic Properties

This work reports on the synthesis of CrO2 thin films by atmospheric pressure CVD using chromium trioxide (CrO3) and oxygen. Highly oriented (100) CrO2 films containing highly oriented (0001) Cr2O3 were grown onto Al2O3(0001) substrates. Films display a sharp magnetic transition at 375 K and a saturation magnetization of 1.92 Bohr magnetons per f.u., close to the bulk value of 2 Bohr magnetons per f.u. for the CrO2. Keywords: Chromium dioxide (CrO2), Atmospheric pressure CVD, Spintronics.Comment: 5 pages, 6 figure

Slow positron beam generator for lifetime studies

A slow positron beam generator uses a conductive source residing between two test films. Moderator pieces are placed next to the test film on the opposite side of the conductive source. A voltage potential is applied between the moderator pieces and the conductive source. Incident energetic positrons: (1) are emitted from the conductive source; (2) are passed through test film; and (3) isotropically strike moderator pieces before diffusing out of the moderator pieces as slow positrons, respectively. The slow positrons diffusing out of moderator pieces are attracted to the conductive source which is held at an appropriate potential below the moderator pieces. The slow positrons have to pass through the test films before reaching the conductive source. A voltage is adjusted so that the potential difference between the moderator pieces and the conductive source forces the positrons to stop in the test films. Measurable annihilation radiation is emitted from the test film when positrons annihilate (combine) with electrons in the test film

Tribological properties of Ag/Ti films on Al2O3 ceramic substrates

Ag solid lubricant films, with a thin Ti interlayer for enhanced adhesion, were sputter deposited on Al2O3 substrate disks to reduce friction and wear. The dual Ag/Ti films were tested at room temperature in a pin-on-disk tribometer sliding against bare, uncoated Al2O3 pins under a 4.9 N load at a sliding velocity of 1 m/s. The Ag/Ti films reduced the friction coefficient by 50 percent to about 0.41 compared to unlubricated baseline specimens. Pin wear was reduced by a factor of 140 and disk wear was reduced by a factor of 2.5 compared to the baseline. These films retain their good tribological properties including adhesion after heat treatments at 850 C and thus may be able to lubricate over a wide temperature range. This lubrication technique is applicable to space lubrication, advanced heat engines, and advanced transportation systems