Ultrahigh-Density HfO₂ Nanodots for Flash Memory Scaling

Abstract

The use of a permanent magnetic field in superconducting magnetic fusion devices impedes conditioning by glow discharges as actually applied in most pulsed machines. An alternative has been studied in Tore Supra for this purpose with a 3.8 T permanent field: a discharge produced by ion cyclotron range of frequency wave injection (ICRF). Helium ICRF discharge conditioning (ICRF-DC) has already been shown to desaturate the deuterium-loaded carbon first wall efficiently. In this paper, we describe how D 2 ICRF-DC can be applied to clean the wall or change its hydrogen isotopic ratio. This is achieved by pumping wall-desorbed molecules induced by particle bombardment from the ICRF plasma. The conditioning efficiency is optimized as a function of two input parameters: the gas pressure and the applied power. A plasma characterization is also given as a function of these parameters and a global model has been used to compare the experimental results and to interpret the main processes to which the neutral and charged species are subjected. The key to optimizing ICRF-DC is the wave ion heating to produce energetic particle bombardment of the first wall, while still achieving a low electron density, low-temperature plasma (n e 10 17 m −3 , T e < 6 eV) to avoid reionization and redeposition of wall-desorbed neutrals before they can be evacuated by the torus pumping system. † Permanent address: Asociacion Euratom-Ciemat, Av. Complutense 22,

Performance Improvement of a Nonvolatile UV TD Sensor Using SAHAOS with a High Temperature Annealed, Partially Nano-Crystallized Trapping Layer

“…UV-induced charges can be trapped not only in HfAlO nanocrystals, but also in amorphous regions of the HfAlO trapping layer. Therefore, it is understood that the partially nanocrystallized HfAlO trapping layer has a higher trap density than the complete amorphous HfAlO trapping layer [15,16,17,18,19,20]. The author thinks that that the nanocrystallization-induced trap generation enhances the trap density.…”

“…The author thinks that that the nanocrystallization-induced trap generation enhances the trap density. Therefore, the SAHAOS-T3 and SAHAOS-T2 (hereafter PNC-SAHAOS) with a PNC-HfAlO trapping layer show a larger trap density compared to SAHAOS-T1 with an amorphous HfAlO trapping layer [15,16,17,18,19,20].…”

“…As illustrated in Figure 8a,b, the gate dielectric leakage current of the SAHAOS-T3 and SAHAOS-T2 devices at V G = 30 V before and after UV irradiation has been significantly improved, compared with the SAHAOS-T1 and STD-SANOS device. Therefore, the author believes that the HfAlO nanocrystals highly capture localized charges and effectively suppress lateral charge migration, which can act as current leakage paths [15,16,17,18,19,20].…”

“…The partially nanocrystallized HfAlO thin films of PNC-SAHAOS will capture highly localized charges and effectively inhibit the charge leakage path. Hence, for PNC-SAHAOS, there will be a decrease in the charge leakage path of HfAlO films, which can result in better charge retention [15,16,17,18,19,20]. In the partially crystallized HfAlO trapping layers, nanocrystals are embedded in amorphous HfAlO; thus, injected electrons can be trapped in HfAlO nanocrystals and the amorphous HfAlO matrix.…”