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The retention, reliability and security of data stored in Non Volatile Memories (NVM) are problems of utmost importance for the microelectronics industry. All these issues could be addressed by physically reading the memory content. A method to deduce memory organization and then to read data in Flash-EEPROM devices is presented. It is based on failure analysis techniques such as Focused Ion Beam (FIB), Scanning Kelvin Probe Microscopy (SKPM) and Scanning Capacitance Microscopy (SCM). An application is demonstrated on the Flash memory of a Programmable Integrated Circuit (PIC) from Microchip dedicated to smart card applications.

In order to study the spin dependent transport mechanisms through a small collection of nano-objects, we propose an original fabrication process of ferromagnetic nanoelectrodes (NEs). It consists in etching, through a negative PMMA mask patterned by high-dose HREBL exposure, the continuous ferromagnetic layer deposited in optimal conditions by sputtering under ultra high vacuum into couples of planar nanoelectrodes (NEs) separated by a nanometric gap. The main advantage of this approach is to guarantee a priori a better crystalline and magnetic quality of the NEs. In this paper, we describe in detail the impact of various parameters such as the electron beam dose, the coded layout NE gap, the layer development, the inversed PMMA removal as well as the ion beam etching parameters …. Observations by scanning electron microscopy (SEM) and atomic force microscopy (AFM) reveal that a 270 nC cm−1 is required to reverse the PMMA tone and provide a strong etching mask. NE gap from 5 nm to several tens of nm were obtained in a reproducible way. Moreover, thanks to the micropads created by a first HREBL stage, the samples were electrically bonded to a gold base plate allowing low current electrical measurements. These measurements on Co NEs showed that 5–20 nm range separated gaps have resistance in the range of hundreds G Ω to T Ω . These measurements correlated with energy dispersive spectroscopy (EDS) observations demonstrate that this process provides well adapted systems for the investigation of nano-object electrical properties.

This article is a study of copper, indium, and gallium interdiffusions in In2Se3/CuGaSe2/SnO2/glass thin film heterostructures annealed at different temperatures. The use of CuGaSe2 material in place of Cu(In,Ga)Se2 is only required by the indium diffusion studies. The CuGaSe2 layers were grown by close-spaced vapor transport for two types of sources having different grain sizes. The In2Se3 films were deposited by thermal evaporation. The heterostructures were annealed in vacuum at different temperatures and analyzed by secondary ion mass spectroscopy (SIMS). The copper, indium, and gallium SIMS concentration profiles show that the copper diffuses up to the In2Se3 film surface and that the indium can diffuse far away from the In2Se3/CuGaSe2 interface towards SnO2. The copper, indium, and gallium diffusions were studied and the interdiffusion parameters were computed. The simultaneous interdiffusions of copper and indium induces the formation of a p–n junction responsible for the photovoltaic effect of the...

We have demonstrated by CW electroluminescence the ability to inject spin polarized electrons through Co/Al2O3/GaAs structures into p-doped InAs/GaAs quantum dots embedded in a PIN GaAs light emitting diode. The spin relaxation processes in the p-doped quantum dots are characterized independently by optical measurements (time and polarization–resolved photoluminescence). The measured electroluminescence circular polarization is about 15% at 1.7 K in a 2 T magnetic field, leading to an estimation of the electrical spin injection yield of about 35%. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

This paper presents a sample preparation study on a FIB based X-section. It shows that wet etching is a simple and reproducible solution for the decoration of both implanted and deposited layers. The methodology is applicable on bare or packaged dice. Results with EBIC on FIB cross-sections were also obtained. A specific double FIB box method was developed and characterized to improve spatial resolution of EBIC.

We have investigated the electron and hole spin dynamics in p-doped semiconductor InAs/GaAs quantum dots by time resolved photoluminescence. We observe a decay of the average electron spin polarisation down to 1/3 of its initial value with a characteristic time of TD » 500ps. We attribute this decay to the hyperfine interaction of the electron spin with randomly orientated nuclear spins. Magnetic field dependent studies reveal that this efficient spin relaxation mechanism can be suppressed by a field of the order of 100mT. In pump-probe like experiments we demonstrate that the resident hole spin, "written" with a first pulse, remains stable long enough to be "read" 15ns later with a second pulse.

We have demonstrated by electroluminescence the injection of spin polarized electrons through Co/Al2O3/GaAs tunnel barrier into p-doped InAs/GaAs quantum dots embedded in a PIN GaAs light emitting diode. The spin relaxation processes in the p-doped quantum dots are characterized independently by optical measurements (time and polarization resolved photoluminescence). The measured electroluminescence circular polarization is about 15 % at low temperature in a 2T magnetic field, leading to an estimation of the electrical spin injection yield of 35%. Moreover, this electroluminescence circular polarization is stable up to 70 K., Comment: 6 pages, 4 figures

DX centers have been detected in vertical transport experiments of GaAs-AlAs superlattices. We studied miniband conduction properties of such semiconductor structures in presence of high hydrostatic pressures and controlled temperature. Hystheresis effect in the current-voltage characteristics was observed. We show that miniband transport properties are dependent on the path of the pressure cycle imposed to the sample. It is clear from our results that DX centers are present in the active superlattice region. We propose that the energy associated with DX states in superlattice results from a "hybridization" of DX centers of both GaAs and AlAs bulk materials.

We have analysed the vertical transport properties of a GaAs/AlAs short period superlattice as the crossed magnetic field is rotated in the plane of the layers. The rotation of the magnetic field has been used to probe the interface roughness along the different in-plane crystallographic directions. Two maxima separated by 180° in the current intensity have been observed when the magnetic field is rotated through 360°. We interpret our results in terms of anisotropic scattering from elliptical interface defects of which the great axis is along [110] and the minor one along [110].

Dislocation mobility is studied by low frequency internal friction in undoped InSb between 0.1 and 0.98 T m . Samples characterized by a mainly screw dislocations substructure generated by low temperature (403 K) deformation, reveal two high amplitude peaks located at 570 and 725 K. The 570 K-peak symmetrically shaped is explained as an intrinsic relaxation peak of screw dislocations moving by double kink nucleation followed by their lateral propagation. The peak analysis leads to an activation energy 1.27±0.11 eV, close to the apparent activation energy of the InSb plastic deformation Etude a basse frequence (1 Hz) entre 0,1 et 0,98 T m . Mise en evidence de deux pics d'amplitude importante, a 570 et 725 K, dans une sous-structure composee essentiellement de dislocations vis produites par deformation plastique a 403 K. Interpretation du pic symetrique a 570 K par une relaxation intrinseque de dislocation vis par germination de doubles decrochements suivie de la propagation laterale de chaque decrochement