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[en] Based on a model suggested by the authors (Eknoyan, Yang and Sze. Solid State Electron.; 20:285 (1977)), diodes having the multilayered n⁺ipνn⁺ structure have been fabricated from silicon material using ion implantation techniques. Systematic descriptions of their fabrication and evaluation are presented. Microwave CW oscillations at C-band (approximately 7.5 Ghz) have been observed in some of these devices. The measured maximum power output was in the range of 40 mw and the efficiency was approximately 5%. The obtained efficiency is the best reported for any BARITT diode. This result indicates that the retarding field region in BARITT diodes may be used advantageously to provide a favorable phase delay between the injected current and the a.c. voltage and leads to improved efficiency BARITT oscillators. (author)

[en] In this study, a distributed charge storage with GeO₂ nanodots is demonstrated. The mean size and aerial density of the nanodots embedded in SiO₂ are estimated to be about 5.5 nm and 4.3x10¹¹ cm^-2, respectively. The composition of the dots is also confirmed to be GeO₂ by x-ray absorption near-edge structure analyses. A significant memory effect is observed through the electrical measurements. Under the low voltage operation of 5 V, the memory window is estimated to ∼0.45 V. Also, a physical model is proposed to demonstrate the charge storage effect through the interfacial traps of GeO₂ nanodots

[en] This study focuses on the influence of a hydrogen plasma treatment on electrical properties of tungsten nanocrystal nonvolatile memory. The X-ray photon emission spectra show that, after the hydrogen plasma treatment, a change in binding energy occurs such that Si^x+ and Si^y+ peaks appear at a position that is shifted about 2.3 and 3.3 eV from Si⁰⁺ in Si 2p spectra. This indicates that Si dangling bonds are passivated to form a Si-H bond structure in the SiO₂. Furthermore, the transmission electron microscopy shows cross-sectional and plane-view for the nanocrystal microstructure after the hydrogen plasma treatment. Electrical measurement analyses show improved data retention because the hydrogen plasma treatment enhances the quality of the oxide surrounding the nanocrystals. The endurance and retention properties of the memory device are improved by about 36% and 30%, respectively.

[en] In this work, an oxygen plasma treatment was used to improve the memory effect of nonvolatile W nanocrystal memory, including memory window, retention and endurance. To investigate the role of the oxygen plasma treatment in charge storage characteristics, the X-ray photon-emission spectra (XPS) were performed to analyze the variation of chemical composition for W nanocrystal embedded oxide both with and without the oxygen plasma treatment. In addition, the transmission electron microscopy (TEM) analyses were also used to identify the microstructure in the thin film and the size and density of W nanocrystals. The device with the oxygen plasma treatment shows a significant improvement of charge storage effect, because the oxygen plasma treatment enhanced the quality of silicon oxide surrounding the W nanocrystals. Therefore, the data retention and endurance characteristics were also improved by the passivation.

[en] The authors provide the formation and memory effects of W nanocrystals nonvolatile memory in this study. The charge trapping layer of stacked a-Si and WSi₂ was deposited by low pressure chemical vapor deposition (LPCVD) and was oxidized by in-situ steam generation system to form uniform W nanocrystals embedded in SiO₂. Transmission electron microscopy analyses revealed the microstructure in the thin film and X-ray photon-emission spectra indicated the variation of chemical composition under different oxidizing conditions. Electrical measurement analyses showed the different charge storage effects because the different oxidizing conditions influence composition of trapping layer and surrounding oxide quality. Moreover, the data retention and endurance characteristics of the formed W nanocrystal memory devices were compared and studied. The results show that the reliability of the structure with 2% hydrogen and 98% oxygen at 950 ^oC oxidizing condition has the best performance among the samples.

[en] This study investigates the temperature-dependent memory characteristics of polycrystalline silicon thin-film transistors with oxide/nitride/oxide stack gate dielectrics and N⁺ poly-Si gate structures for nonvolatile memory application. As the device was programmed by Fowler-Nordheim tunneling at high temperature, some electrons captured in shallow traps could obtain enough thermal energy to de-trap to the gate, resulting in low programming efficiency. As the programming time increases, the hole injection through the blocking oxide from the gate would further lead the threshold voltage to decrease. In addition, the retention characteristic of the device programmed at higher temperature exhibits better charge storage ability. Because the electrons trapped in the shallow traps of the nitride layer can be easily de-trapped when temperature rises, the memory characteristics are mainly dominated by charges stored in the deep traps.