Alexandre Hubert

Experimental comparison of programming mechanisms in 1T-DRAM cells with variable channel length

The bulk DRAM scaling requirements have lead to many different concepts of capacitor-less single-transistor (1T) DRAM. Amongst the various effects used to program the cell, this study is focused on the Impact Ionization (II), the most common mechanism to store charges in the body of the cell, and the Meta-Stable Dip (MSD) effect. Dynamic measurements are presented showing the impact of the gate length reduction on both the II and the MSD programming mechanisms. It is found that MSD is less impacted by the scaling of standard SOI MOSFETs without specific optimization. Those attractive performances result from the dynamic coupling between the front and back gates in Fully Depleted SOI (FDSOI) transistors.

Modeling stress retarded self-limiting oxidation of suspended silicon nanowires for the development of silicon nanowire-based nanodevices

In this paper, we present a model for the oxidation of silicon nanowires (NWs) based on a modification of the cylindrical Deal and Grove equation and taking into account stress effects associated with non-uniform deformation of the oxide by viscous flow. The validity of this model has been tested on a set of experimental results describing the thermal oxidation of suspended silicon NWs. The NWs oxidation is examined upon different atmospheres (pure O2 and H2O) and at different thermal budgets by scanning electron microscopy and transmission electron microscopy measurements. The good agreement between the experimental results and the simulations confirm the validity of the key model assumptions: the SiO2 flow can be approximated as purely viscous and the non-linear effects of shear stress on oxide viscosity [S. M. Hu, J. Appl. Phys. 64, 323 (1988)] can be neglected. In addition, the model gives some interesting insight about the physics of the oxidation process. In particular, we demonstrate that the compr...

New type of magnetic domains ― the small lozenge type configuration in amorphous thin films

Abstract Small isolated flat domains in the shape of lozenges with in-plane magnetization have been investigated in Co-Ni-P and Co-Ti amorphous layers. Such domains may be used for high density non-volatile shift register memories. Domain observations are made using the longitudinal Kerr effect. Nucleation is obtained either by overcoming the anisotropy field via a locally and temporary applied high field or from splitting a large zigzag domain into isolated lozenges. To stabilize the domains two constant fields having opposite direction are required. By this method stable domains 5 μ m in length have been observed. Experimental curves showing the variation of the length and width of domains for different configurations of the applied fields are presented. The results are compared to numerical computations. The theoretical model is discussed and the role played by the magnetostatic energy emphasized. Finally, theoretical predictions to obtain smaller domains are presented.

180° wall oscillation in uniaxial in-plane thin films

Abstract Transformation of a 180° asymmetric Bloch wall into an asymmetric Neel wall in NiCoP amorphous film occurs in the ac (H2) and Ht fields applied simultaneously in the easy and hard directions, respectively. The “dead gap” during which the wall does not oscillate (in increasing Ht-field) is understood to be due to the immobile Bloch/Neel asymmetric lines generated during the wall transformation.

Domain propagation along the hard axis in a onefold layer

Abstract Flat lozenge-type domains in a NiCoP onefold layer may propagate under the influence of a transverse field and two electric currents. The domain behaviour was analyzed step by step using digital image processing in the static and semidynamic conditions. The two phases of the domain propagations ate due to the local variable coercivity, domain wall transformation freom asymmetric Bloch into asymmetric Neel type and domain tip coercivity.

Small planar domains in amorphous thin films: Nucleation and equilibrium conditions (abstract)

The purpose of this work is to investigate a new type of small flat domain in the shape of lozenges. Such domains may be used for high‐density nonvolatile shift register memories [C. Battarel, R. Morille, and A. Caplain, IEEE Trans. Magn. July (1983)]. Experimental and theoretical results for nucleation and stability of small lozenge domains less than 10 μm in length in Co–Ni–P and CoTi [G. Suran, K. Ounadjela, and J. Sztern (this Proceedings)] amorphous thin films 1500 A thick are presented. The films have a low coercivity (Hc ∼1 Oe) and a significant in‐plane uniaxial anisotropy (HK ∼35 Oe). The domains were observed in an optical microscope by longitudinal Kerr effect using an experimental method described by Prutton. Domain nucleation is obtained by applying a local field higher than HK. It must be emphasized that to stabilize the domain two constant fields having opposite direction are required: H1 applied inside the domain and parallel to its magnetization; H2 parallel to the main magnetization of t...