In recent years titanium nitride is being considered as a very promisingplasmonic material for data storage applications as it exhibits a pronouncedplasmonic dipolar resonance and has high thermal stability. However, there is alack of research where higher order resonance modes are examined. We addressthis here by performing angle dependent spectral transmission measurementsnanodisks arrays made from titanium nitride. The measurements show strongpolarization dependence with s-polarized light causing excitation of thequadrupole and higher order resonance plasmonic modes. These higher order modesare required for the state-of-the-art designs of near-field transducers. This,together with its outstanding thermal properties, makes TiN a favourablematerial for data storage applications.

In this work we explore the mechanisms responsible for Random Telegraph Noise(RTN) fluctuations in HfOx Resistive Random Access Memory (RRAM)devices. The statistical properties of the RTN are analyzed in many operatingconditions exploiting the Factorial Hidden Markov Model (FHMM) to decompose themultilevel RTN traces in a superposition of two-level fluctuations. This allowsthe simultaneous characterization of individual defects contributing to the RTN.Results, together with multi-scale physics-based simulations, allows thoroughlyinvestigating the physical mechanisms which could be responsible for the RTNcurrent fluctuations in the two resistive states of these devices, includingalso the charge transport features in a comprehensive framework. We consider twopossible options, which are the Coulomb blockade effect and the possibleexistence of metastable states for the defects assisting charge transport.Results indicate that both options may be responsible for RTN currentfluctuations in HRS, while RTN in LRS is attributed to the temporary screeningeffect of the charge trapped at defect sites around the conductive filament.

Feasibility of multiwavelength Raman spectroscopy was studied as a potentialin-line monitoring technique for grain size distribution in channel poly-Si usedin three dimensional stacked NAND (3D NAND) Flash memory devices. Variouschannel poly-Si materials in 3D-NAND Flash memory devices, converted fromchemical vapor deposition (CVD) grown a-Si, were characterized usingnon-contact, multiwavelength Raman spectroscopy and high resolutioncross-sectional transmission electron microscopy (HRXTEM). The Ramancharacterization results were compared with HRXTEM images. The correlationbetween the grain size distribution characterized by multiwavelength Ramanspectroscopy and “on current” (ION) of 3D NANDFlash memory devices was investigated. Good correlation between these techniqueswas seen. Multiwavelength Raman spectroscopy is very promising as anon-destructive in-line monitoring technique for grain size distribution inchannel poly-Si used in 3D NAND Flash memory devices.

Reversible changes in the conductivity of HfO2 dielectric film betweenhigh and low resistive states of a metal-insulator-metal memory cell wereattributed to the formation of oxygen vacancies and their clustering across theinsulator layer. In this study we present an innovative model which includesgeneration of two-charged states of oxygen vacancies at the anode, theirdiffusion to the cathode, transformation to one-charged state, and then toneutral vacancies. Vacancy clusters in the insulator layer are built from onlyneutral vacancies, while the kinetics of the clustering process is controlled bydiffusion of mobile one-charged state vacancies. Resistive switching is treatedas the formation of critical size vacancy cluster which provides continuousconductive path through the dielectric layer. Good agreement between theexperimental data and the theoretical bias and temperature dependences for thedelay time was obtained.

Surface smoothing of Ru used as underlayer of magnetic tunneling junctions (MTJ)in magneto-resistive random access memory (MRAM) was carried out with gascluster ion beam (GCIB) in order to improve device characteristics. For Rufilms, surface smoothing with 5 kV N2-GCIB irradiation was effective,and CoFe films deposited on smoothed Ru surface also showed smooth surface. Fromthe hysteresis loop measurements of MTJ formed on smoothed Ru withN2-GCIB, it showed improvement of inter-layer coupling magnetic field(Hin) with decreasing the surface roughness of underlayer Ru. Itis expected that surface roughness of MgO in MTJ was also improved by smoothingof underlayer Ru with N2-GCIB.

Effects of defect on ferroelectric stability in PbTiO3 (PTO) thinfilms have been investigated using molecular dynamics with first-principleseffective Hamiltonian. In this paper, oxygen vacancy (Vo) has been considered tostudy the hysteresis loop, spontaneous polarization as a function of filmthickness. Vo has been modeled as a charged point defect. Density functionaltheory (DFT) calculations are performed to determine the Vo-induced localizedfields (both mechanical and electrical) and the calculated DFT results are usedas inputs to molecular dynamics simulations in a large system. The strain fieldinduced by the Vo is calculated by DFT calculations and fitted by the continuumstrain modeling, and the electrostatic field is given by the superposition ofthe Vo-induced field and the external field. Vo significantly reduces thespontaneous polarization and increases the critical thickness.

We fabricated ferroelectric (Pb,La)(Zr,Ti)O3 (PLZT) capacitors withSn:In2O3 (ITO) or Pt top electrodes and investigatedthe ferroelectric properties of these PLZT capacitors. The shape ofpolarization–voltage hysteresis loops was essentially unchanged andthe decrease in the remnant polarization of the ITO/PLZT/Pt capacitors wassmaller than that of the Pt/PLZT/Pt capacitors after annealing with 3%D2 (in N2) at 200°C and 1 Torr(i.e., FGAD). Time of flightsecondary mass spectrometry revealed that the D atoms were incorporated into thePLZT film of the Pt/PLZT/Pt capacitors after 3% D2 annealing,resulting in a decrease in the ferroelectric properties. In comparison, no D ionsignal was detected in the PLZT film after FGAD for ITO/PLZT/Ptcapacitors.

Topological (GeTe)/(Sb2Te3) superlattices (SL) are ofpractical interest for memory applications because of different mechanism ofelectric conductance switching in the crystalline phase. In the work, electricalswitching behavior of individual SL grains was examined employing a multimodescanning probe microscope (MSPM) in a lithography mode at room temperature.Using programmed bias voltage with different amplitude and pulse duration, weobserved the position-dependent variations of the switching voltage and thecurrent injection delay for [(GeTe)2(Sb2Te3)]4 SLs on Si(100). The results sheda light on the role of electric field and hot-electron injection on the SLconductance switching.