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Gradual switching between multiple resistance levels is desirable for analog in-memory computing using resistive random-access memory (RRAM). However, the filamentary switching of HfOx-based conventional RRAM often yields only two stable memory states instead of gradual switching between multiple resistance states. Here, we demonstrate that a thermal barrier of Ge2Sb2Te5 (GST) between HfOx and the bottom electrode (TiN) enables wider and weaker filaments, by promoting heat spreading laterally inside the HfOx. Scanning thermal microscopy suggests that HfOx + GST devices have a wider heating region than control devices with only HfOx, indicating the formation of a wider filament. Such wider filaments can have multiple stable conduction paths, resulting in a memory device with more gradual and linear switching. The thermally enhanced HfOx + GST devices also have higher on/off ratio (>103) than control devices (<102) and a median set voltage lower by approximately 1 V (∼35%), with a corresponding reduction of the switching power. Our HfOx + GST RRAM shows 2× gradual switching range using fast (∼ns) identical pulse trains with amplitude less than 2 V. [ABSTRACT FROM AUTHOR]

Presents a study that developed a three-dimensional model for low-pressure chemical-vapor-deposition step coverage in trenches and circular vias. Derivation of the basic equations; Method; Results and discussion; Conclusion.

Presents a study which performed plasma nitridation of silicon at low temperatures in nitrogen plasma generated by microwave discharge. Method of the study; Results and discussion; Conclusion.

In this letter, we investigate the electrical behavior of vacancy VGe defects in Ge at various thermal annealing conditions through electrochemical capacitance–voltage analysis. Then, the effects of the annealing process on Ge \n^+/\p junction diodes were also studied with J-V, transmission electron microscopy, and secondary ion mass spectroscopy measurements in the aspects of point-defect healing and dopant diffusion/loss phenomena. The V \rm Ge defects tend to heal by recombining with Ge interstitial atoms as the annealing process temperature increases. However, the diffusion/loss problems of P atoms in Ge become severe at above 500 ^\circ\C. Therefore, an optimal postfabrication annealing process at 600 ^\circ\C is proposed in terms of point-defect healing and dopant diffusion/loss reduction. [ABSTRACT FROM PUBLISHER]

Recent experiments have demonstrated a reduction of Fermi-level pinning in contacts to n-type Ge by the insertion of a thin tunnel barrier at the interface. The presence of fixed charge in these interface layers can contribute to Schottky-barrier reduction. This work theoretically studies the effect of tunnel-barrier fixed charge on the specific contact resistivity. By simulating various tunnel-barrier materials and fixed-charge densities, we estimate the magnitude of fixed charge required for this mechanism to play an important role in Fermi-level unpinning. [ABSTRACT FROM PUBLISHER]

We report on selected results of an extensive study of SiO2 nitridation in an NH3 ambient obtained primarily using Auger sputter profiling. By investigating a large matrix of samples, we have sorted out the discrepancies present in the literature concerning the kinetics of the nitridation process. Two major new results obtained are the quantitative observation of oxygen depletion in the nitroxide ‘‘bulk’’ region and, consistent with a recent report by R. Vasquez, M. Hecht, F. Grunthaner, and M. Naiman [Appl. Phys. Lett. 44, 969 (1984)], the reoxidation of the interface by oxygen presumably liberated by the bulk exchange reaction. [ABSTRACT FROM AUTHOR]