On the impact of heavy doping on grown-in defects in Czochralski-grown silicon

The effects of heavy doping of Si on grown-in void size-density distributions and on Flow Pattern Defect (FPD) and Secco Etch Pit Defect (SEPD) density are discussed. Grown-in defects are studied using Scanning Infra Red Microscopy (SIRM) and Secco etching. Doping with 10(20) Ge atoms cm(-3) has a limited effect on the grown-in void size-density distribution but has a clear effect on the FPD density. The observed lower FPD density is most probably related to a decrease of the multiple void density. Co-doping with 10(20) B atoms cm(-3) leads to strong a suppression of the void density by nearly two orders of magnitude in agreement with the reported strong reduction of Crystal Originated Particle (COP) density in low resistivity p-type Si

Resistive switching in p-type nickel oxide/n-type indium gallium zinc oxide thin film heterojunction structure

We report a p-type nickel oxide/n-type indium gallium zinc oxide (p-NiO/n-IGZO) thin film heterojunction structure for resistive switching memory application. The as-fabricated structure exhibits the normal p-n junction behaviors with good rectification characteristic. The structure is turned into a bipolar resistive switching memory by a forming process in which the p-n junction is reversely biased. The device shows good memory performances; and it has the capability of multibit storage, which can be realized by controlling the compliance current or reset stop voltage during the switching operation. The mechanisms for both the forming process and bipolar resistive switching are discussed; and the current conduction at the low- and high-resistance states are examined in terms of temperature dependence of the current-voltage characteristic of the structure.NRF (Natl Research Foundation, S’pore)ASTAR (Agency for Sci., Tech. and Research, S’pore)MOE (Min. of Education, S’pore

QTLs regulating the contents of antioxidants, phenolics, and flavonoids in soybean seeds share a common genomic region

Soybean seeds are a rich source of phenolic compounds, especially isoflavonoids, which are important nutraceuticals. Our study using 14 wild- and 16 cultivated-soybean accessions shows that seeds from cultivated soybeans generally contain lower total antioxidants compared to their wild counterparts, likely an unintended consequence of domestication or human selection. Using a recombinant inbred population resulting from a wild and a cultivated soybean parent and a bin map approach, we have identified an overlapping genomic region containing major quantitative trait loci (QTLs) that regulate the seed contents of total antioxidants, phenolics, and flavonoids. The QTL for seed antioxidant content contains 14 annotated genes based on the Williams 82 reference genome (Gmax1.01). None of these genes encodes functions that are related to the phenylpropanoid pathway of soybean. However, we found three putative Multidrug And Toxic Compound Extrusion (MATE) transporter genes within this QTL and one adjacent to it (GmMATE1-4). Moreover, we have identified non-synonymous changes between GmMATE1 and GmMATE2, and that GmMATE3 encodes an antisense transcript that expresses in pods. Whether the polymorphisms in GmMATE proteins are major determinants of the antioxidant contents, or whether the antisense transcripts of GmMATE3 play important regulatory roles, awaits further functional investigations

<i>o</i>‑Nitrobenzyl-Based Photobase Generators: Efficient Photoinitiators for Visible-Light Induced Thiol-Michael Addition Photopolymerization

In this contribution, three <i>o</i>-nitrobenzyl-based photobase systems were synthesized and evaluated for visible light initiated thiol-Michael addition polymerizations. With a modified structure, the (3,4-methylenedioxy-6-nitrophenyl)-propyloxycarbonyl (MNPPOC) protected base performance exceeds that of the nonsubstituted 2-(2-nitrophenyl)-propyloxycarbonyl (NPPOC) protected base and an ITX sensitized photobase system, with respect to both long-wavelength light sensitivity and photolytic efficiency. In material synthesis, MNPPOC-TMG is capable of initiating photo thiol-Michael polymerization efficiently and orthogonally with only limited visible light exposure and generating a highly homogeneous cross-linked polymer network. This approach enables the thiol-Michael “click” reaction to be conducted with a low-energy, visible light irradiation and, thus, expands its applications in biocompatible and UV sensitive materials

First results from a next-generation off-plane X-ray diffraction grating

Future NASA X-ray spectroscopy missions will require high throughput, high resolution grating spectrometers. Off-plane reflection gratings are capable of meeting the performance requirements needed to realize the scientific goals of these missions. We have identified a novel grating fabrication method that utilizes common lithographic and microfabrication techniques to produce the high fidelity groove profile necessary to achieve this performance. Application of this process has produced an initial pre-master that exhibits a radial (variable line spacing along the groove dimension), high density (>6000 grooves/mm), laminar profile. This pre-master has been tested for diffraction efficiency at the BESSY II synchrotron light facility and diffracts up to 55% of incident light into usable spectral orders. Furthermore, tests of spectral resolving power show that these gratings are capable of obtaining resolutions well above 1300 (λ/Δλ) with limitations due to the test apparatus, not the gratings. Obtaining these results has provided confidence that this fabrication process is capable of producing off-plane reflection gratings for the next generation of X-ray observatories