Kasvutingimuste ja -aluste mõju TiO2 aatomkihtsadestumisele

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RRAM Memories with ALD High-K Dielectrics: Electrical Characterization and Analytical Modeling

Resistive switching phenomena with adequate repetitiveness on Ta2O5-TiO2-Ta2O5 and TiO2-Ta2O5-TiO2 stacks are reported. In particular, 5–nm-thick TiO2 films embedding a monolayer of Ta2O5 show the best behavior in terms of bipolar cycles loop width, with separate low and high resistive states up to two orders of magnitude. Tantalum oxide layer increases the defect density in titania that becomes less leaky, and thus, resistive switching effects appear. Small signal ac parameters measured at low and medium frequencies, namely capacitance and conductance, also show hysteretic behavior during a whole bipolar switching cycle. This means that the memory state can be read at 0 V, without any power consumption. High-frequency measurements provide information about dipole relaxation frequency values in the dielectric bulk, and this can be connected with resistive switching behavior. Finally, a double tunneling barrier model fits I-V curves at the low-resistance state even at the bias range where reset occurs and a sharp fall takes place

Memory maps : Reading RRAM devices without power consumption

Producción CientíficaA comparative study of MIM-RRAM structures with different insulator materials is presented. Admittance memory mapping was carried out at 0 V dc bias, revealing two clearly separated states, both in terms of conductance and susceptance. The memory in the ON state can be modeled by means of a two parameter (resistance and inductance) equivalent circuit. The parameter extraction provides memory maps for the resistance and the inductance as well. The transition shapes between the ON and OFF state are different for each structure due to specific physical mechanisms.Ministerio de Economía, Industria y Competitividad - Fondo Europeo de Desarrollo Regional (grant TEC2014-52152-C3-3-R)Fondo Europeo de Desarrollo Regional (project TK134)Estonian Research Agency (grants IUT2-24 and PRG4

Atomic layer deposition of titanium oxide films on As-synthesized magnetic Ni particles : Magnetic and safety properties

Spherical nickel particles with size in the range of 100-400 nm were synthesized by non-aqueous liquid phase benzyl alcohol method. Being developed for magnetically guided biomedical applications, the particles were coated by conformal and antimicrobial thin titanium oxide films by atomic layer deposition. The particles retained their size and crystal structure after the deposition of oxide films. The sensitivity of the coated particles to external magnetic fields was increased compared to that of the uncoated powder. Preliminary toxicological investigations on microbial cells and small aquatic crustaceans revealed non-toxic nature of the synthesized particles.Peer reviewe

Memory maps : Reading RRAM devices without power consumption

´A comparative study of MIM-RRAM structures with different insulator materials is presented. Admittance memory mapping was carried out at 0 V dc bias, revealing two clearly separated states, both in terms of conductance and susceptance. The memory in the ON state can be modeled by means of a two parameter (resistance and inductance) equivalent circuit. The parameter extraction provides memory maps for the resistance and the inductance as well. The transition shapes between the ON an OFF state are different for each structure due to specific physical mechanisms. © The Electrochemical Society.Peer reviewe

TiO2-based metal-insulator-metal structures for future DRAM storage capacitors

Capacitors with TiO2 and Al-doped TiO2 dielectric films grown by atomic layer deposition exhibit promising properties for application in DRAM technology for 20 nm node and beyond. For stabilization of the high dielectric constant rutile TiO2 phase RuO2 thin films were employed as a bottom electrode. The capacitors with the equivalent oxide thickness below 0.5 nm show leakage current below 10-7 A/cm2 at voltage 0.8 and 0.6 V, respectively. Current distribution study using Conductive AFM studies revealed preferential leakage current flow through grains. Low equivalent oxide thickness and low leakage currents of TiO2-based capacitors confirm that they can be considered as an alternative to the SrTiO3 DRAM capacitors