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Flash memory devices--that is, non-volatile computer storage media that can be electrically erased and reprogrammed--are vital for portable electronics, but the scaling down of metal-oxide-semiconductor (MOS) flash memory to sizes of below ten nanometres per data cell presents challenges. Molecules have been proposed to replace MOS flash memory (1), but they suffer from low electrical conductivity, high resistance, low device yield, and finite thermal stability, limiting their integration into current MOS technologies. Although great advances have been made in the pursuit of molecule-based flash memory (2), there are a number of significant barriers to the realization of devices using conventional MOS technologies (3-7). Here we show that core-shell polyoxometalate (POM) molecules (8) can act as candidate storage nodes for MOS flash memory. Realistic, industry-standard device simulations validate our approach at the nanometre scale, where the device performance is determined mainly by the number of molecules in the storage media and not by their position. To exploit the nature of the core-shell POM clusters, we show, at both the molecular and device level, that embedding [[[(Se(IV)[O.sub.3]).sub.2]].sup.4-] as an oxidizable dopant in the cluster core allows the oxidation of the molecule to a [[Se[(V).sub.2][O.sub.6]].sup.2-] moiety containing a {Se(v)-Se(v)} bond (where curly brackets indicate a moiety, not a molecule) and reveals a new 51 oxidation state for selenium. This new oxidation state can be observed at the device level, resulting in a new type of memory, which we call 'write-once-erase'. Taken together, these results show that POMs have the potential to be used as a realistic nanoscale flash memory. Also, the configuration of the doped POM core may lead to new types of electrical behaviour (9-11). This work suggests a route to the practical integration of configurable molecules in MOS technologies as the lithographic scales approach the molecular limit (12)., To engineer the flash memory devices, we selected a core-shell POM 'Dawson-like' archetype as the functional part of the switching node with the general formula [[[M.sub.18][O.sub.54][(X[O.sub.n]).sup.2]].sup.m-] (where M = Mo [...]

Siliconnanowires have been patterned with mean widths down to 4 nm usingtop-down lithography and dry etching. Performance-limiting scatteringprocesses have been measured directly which provide new insight intothe electronic conduction mechanisms within the nanowires. Resultsdemonstrate a transition from 3-dimensional (3D) to 2D and then 1Das the nanowire mean widths are reduced from 12 to 4 nm. The importanceof high quality surface passivation is demonstrated by a lack of significantdonor deactivation, resulting in neutral impurity scattering ultimatelylimiting the electronic performance. The results indicate the importantparameters requiring optimization when fabricating nanowires withatomic dimensions. [ABSTRACT FROM AUTHOR]

The development of nanofabrication techniques for creating high aspect ratio (~50:1) sub-10nm silicon nanowires (SiNWs) with smooth, uniform, and straight vertical sidewalls using an inductively coupled plasma (ICP) etching process at 20 °C is reported. In particular, to improve the quality and flexibility of the pattern transfer process for high aspect ratio SiNWs, hydrogen silsesquioxane, a high-resolution, inorganic, negative-tone resist for electron-beam lithography has been used as both the resist for defining sub-10nm patterns and the hard mask for etching the underneath silicon material. The effects of SF6/C4F8 gas flow rates, chamber pressure, platen power and ICP power on the etch rate, selectivity, and sidewall profile are investigated. To minimize plasma-induced sidewall damage, moderate plasma excitation power (ICP power of 600W) and low ion energy (platen power of 6-12W) were used. Using the optimized etch process at room temperature (20°C), the authors have successfully fabricated sub-10nm SiNWs, which have smooth vertical sidewall profile and aspect ratios up to ~50:1. This optimized etch combined with a controlled thermal oxidation allows the realization of consistent, reproducible, and reliable SiNW devices with nominal widths from 100nm down to sub-5nm in silicon on top of SiO2 fabricated on silicon on insulator substrates. [ABSTRACT FROM AUTHOR]

Germanium-on-Silicon (Ge-on-Si) avalanche photodiodes (APDs) are of considerable interest as low intensity light detectors for emerging applications. The Ge absorption layer detects light at wavelengths up to ≈ 1600 nm with the Si acting as an avalanche medium, providing high gain with low excess avalanche noise. Such APDs are typically used in waveguide configurations as growing a sufficiently thick Ge absorbing layer is challenging. Here, we report on a new vertically illuminated pseudo-planar Ge-on-Si APD design utilizing a 2 µm thick Ge absorber and a 1.4 µm thick Si multiplication region. At a wavelength of 1550 nm, 50 µm diameter devices show a responsivity of 0.41 A/W at unity gain, a maximum avalanche gain of 101 and an excess noise factor of 3.1 at a gain of 20. This excess noise factor represents a record low noise for all configurations of Ge-on-Si APDs. These APDs can be inexpensively manufactured and have potential integration in silicon photonic platforms allowing use in a variety of applications requiring high-sensitivity detectors at wavelengths around 1550 nm.

Background: There is discordance among studies assessing the impact of race on outcome of patients with Triple Negative Breast Cancer (TNBC). We assessed survival outcomes for African American (AA) versus Caucasian (CA) women with TNBC treated at an urban cancer center in Memphis, TN with a predominant AA patient population., Methods: Patients with Stage I-III TNBC were identified from our breast database. Event free survival (EFS) and Breast cancer specific survival (BCSS) were the primary outcome measures. Cox proportional hazards models were fitted for EFS and BCSS., Results: Of the 124 patients, 71% were AA. No significant association between race and stage (P = 0.21) or menopausal status (P = 0.15) was observed. Median age at diagnosis was significantly lower for AA versus CA women (49.5 vs. 55 years, P = 0.024). 92% of the patients received standard neo/adjuvant chemotherapy, with no significant difference in duration and type of chemotherapy between the races. With a median follow up of 23 months, 28% of AA vs. 19% of CA women had an event (P = 0.37). 3 year EFS and BCSS trended favorably towards CA race (77% vs. 64%, log rank P = 0.20 and 92% vs. 76%, P = 0.13 respectively) with a similar trend noted on multiple variable modeling (EFS: HR 0.62, P = 0.29; BCSS: HR 0.36, P = 0.18). AA women >/=50 years at diagnosis had a significantly worse BCSS than the CA women in that age group (P = 0.012)., Conclusion: Older AA women with TNBC have a significantly worse breast cancer specific survival than their CA counterparts. Overall, there is a trend towards lower survival for AA women compared to Caucasians despite uniformity of tumor phenotype and treatment. The high early event rate, irrespective of race, underscores the need for effective therapies for women with TNBC.