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A novel device structure with a high-k HfO2 charge storage layer and dual tunneling layer (DTL) (SiO2/Si3N4) is presented in this paper. Combining advantages of the high trapping efficiency of high-k materials and enhanced charge injection from the substrate through the DTL, the device achieves a fast program/erase speed and a large memory window. The device demonstrates excellent retention due to its physically thick DTL and also improved endurance without any increase of programming Vth throughout the cyclic test as compared with SONOS Flash memory devices using an Si3N4 trapping layer.

We investigated the trapping properties of high κ material as the charge storage layer in non-volatile flash memory devices using a two-dimensional device simulator, Medici. The high κ material is sandwiched between two silicon oxide layers, resulting in the Silicon-Oxide-High κ-Oxide-Silicon (SOHOS) structure. The trap energy levels of the bulk electron traps in high κ material were determined. The programming and erasing voltage and time using Fowler Nordheim tunneling were estimated by simulation. The effect of deep level traps on erasing was investigated. Also, the effect of bulk traps density, thickness of block oxide and thickness of high κ material on the threshold voltage of the device was simulated.

We fabricated a nonvolatile Flash memory device using Ge nanocrystals (NCs) floating-gate (FG)-embedded in HfAlO high-/spl kappa/ tunneling/control oxides. Process compatibility and memory operation of the device were investigated. Results show that Ge-NC have good thermal stability in the HfAlO matrix as indicated by the negative Gibbs free energy changes for both reactions of GeO/sub 2/+Hf/spl rarr/HfO/sub 2/+Ge and 3GeO/sub 2/+4Al/spl rarr/2Al/sub 2/O/sub 3/+3Ge. This stability implies that the fabricated structure can be compatible with the standard CMOS process with the ability to sustain source-drain activation anneal temperatures. Compared with Si-NC embedded in HfO/sub 2/, Ge-NC embedded in HfAlO can provide more electron traps, thereby enlarging the memory window. It is also shown that this structure can achieve a low programming voltage of 6-7 V for fast programming, a long charge retention time of ten years maintaining a 0.7-V memory window, and good endurance characteristics of up to 10/sup 6/ rewrite cycles. This paper shows that the Ge-NC embedded in HfAlO is a promising candidate for further scaling of FG Flash memory devices.

Kallmann syndrome, a form of idiopathic hypogonadotropic hypogonadism, is characterized by developmental abnormalities of the reproductive system and abnormal olfaction. Despite association of certain genes with idiopathic hypogonadotropic hypogonadism, the genetic inheritance and expression are complex and incompletely known. In the present study, seven Kallmann syndrome pedigrees in an ethnic Han Chinese population were screened for genetic mutations. The exons and intron–exon boundaries of 19 idiopathic hypogonadotropic hypogonadism (idiopathic hypogonadotropic hypogonadism)-related genes in seven Chinese Kallmann syndrome pedigrees were sequenced. Detected mutations were also tested in 70 sporadic Kallmann syndrome cases and 200 Chinese healthy controls. In pedigrees 1, 2, and 7, the secondary sex characteristics were poorly developed and the patients’ sense of smell was severely or completely lost. We detected a genetic mutation in five of the seven pedigrees: homozygous KAL1 p.R191ter (pedigree 1); homozygous KAL1 p.C13ter (pedigree 2; a novel mutation); heterozygous FGFR1 p.R250W (pedigree 3); and homozygous PROKR2 p.Y113H (pedigrees 4 and 5). No genetic change of the assayed genes was detected in pedigrees 6 and 7. Among the 70 sporadic cases, we detected one homozygous and one heterozygous PROKR2 p.Y113H mutation. This mutation was also detected heterozygously in 2/200 normal controls and its pathogenicity is likely questionable. The genetics and genotype–phenotype relationships in Kallmann syndrome are complicated. Classical monogenic inheritance does not explain the full range of genetic inheritance of Kallmann syndrome patients. Because of stochastic nature of genetic mutations, exome analyses of Kallmann syndrome patients may provide novel insights.

Formation of Ge nanocrystals embedded in HfAlO high-k dielectric by co-sputtering of HfO2, Al2O3, and Ge, followed by rapid thermal annealing was demonstrated. Analysis by transmission electron microscopy and x-ray photoelectron spectroscopy confirmed the formation of nonoxidized Ge nanocrystals with a minimum size of about 5nm embedded in HfAlO dielectric. We also demonstrated the application of such nanocrystals in nonvolatile memory devices, achieving a 2.2V memory window as obtained from the C–V characterization of the memory device.

The in situ deposition process of SiGe nanocrystals on SiO2 and HfO2 substrates was studied using Auger electron spectroscopy, atomic force microscopy, and x-ray photoelectron spectroscopy. The Ge concentration in SiGe nanocrystals increased with deposition time at equal Si/Ge flow rates. Analysis indicated that the nucleation of Ge takes place preferentially on prenucleated Si on the dielectric. Memory transistors were fabricated using SiGe nanocrystals and HfO2 tunneling/control dielectrics as a gate stack. Memory effects from floating SiGe nanocrystals in HfO2 were clearly observed at room temperature from metal–oxide–semiconductor field effect transistor devices with a threshold voltage shift of about 0.5 V with the application of +4 V.

We investigated the phase separation of HfO based high dielectric constant (k) material for the application to non-volatile memory devices. We found that Hf0.5Si0.5O2 underwent phase separation upon annealing in the temperature range of 900degC to 1000degC: Hf0.5Si0.5O2 rarr (0.5 - x)/(1 - x) HfO2 + 0.5/(1 - x) Hf2Si 1-xO2 where 0 x) was effective to suppress the lateral migration of charges trapped in HfOx. This article demonstrates the 2-bit memory property attained using the phase separation for the short channel devices with channel length down to 180nm

In this paper, we investigate the chemical vapor deposition (CVD) of Ge nanocrystals (NCs) directly on hafnium oxide HfO2 dielectric for non-volatile memory applications. Germane GeH4 was used as a precursor. Atomic force microscopy (AFM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and scanning electron microscopy (SEM) were used to characterize the Ge NCs. The dependence of the Ge NC size and density on the deposition temperature, deposition time, and flow rate was explored. A high Ge NC density of 1011 cm-2 was obtained at a deposition temperature of 600°C, with a mean diameter of about 16 nm. MOS capacitors with CVD Ge NCs embedded in the HfO2 gate dielectric were fabricated. Hysteresis of capacitance-voltage (C-V) characteristics of capacitors with Ge NCs was observed, demonstrating memory effect.