A Near-Infrared Range Photodetector Based on Indium Nitride Nanocrystals Obtained Through Laser Ablation

Cataloged from PDF version of article.We present a proof-of-concept photodetector that is sensitive in the near-infrared (NIR) range based on InN nanocrystals. Indium nitride nanocrystals (InN-NCs) are obtained through laser ablation of a high pressure chemical vapor deposition grown indium nitride thin film and are used as optically active absorption region. InN-NCs are sandwiched between thin insulating films to reduce the electrical leakage current. Under -1 V applied bias, the recorded photoresponsivity values within 600-1100-nm wavelength range are as high as 3.05 x 10(-2) mA/W. An ultrathin layer of nanocrystalline InN thin film is, therefore, a promising candidate for NIR detection in large area schemes. © 2014 IEEE

Enhanced memory effect via quantum confinement in 16 nm InN nanoparticles embedded in ZnO charge trapping layer

Cataloged from PDF version of article.In this work, the fabrication of charge trapping memory cells with laser-synthesized indium-nitride nanoparticles (InN-NPs) embedded in ZnO charge trapping layer is demonstrated. Atomic layer deposited Al2O3 layers are used as tunnel and blocking oxides. The gate contacts are sputtered using a shadow mask which eliminates the need for any lithography steps. High frequency C-Vgate measurements show that a memory effect is observed, due to the charging of the InN-NPs. With a low operating voltage of 4 V, the memory shows a noticeable threshold voltage (Vt) shift of 2 V, which indicates that InN-NPs act as charge trapping centers. Without InN-NPs, the observed memory hysteresis is negligible. At higher programming voltages of 10 V, a memory window of 5 V is achieved and the Vt shift direction indicates that electrons tunnel from channel to charge storage layer. © 2014 AIP Publishing LL

Comparison of the effects of rapid maxillary expansion and surgically assisted rapid maxillary expansion in the sagittal, vertical and transverse planes

Objective: The aim of this study was to evaluate and compare the effects of rapid maxillary expansion (RME) and surgically assisted RME (SARME) in the sagittal, vertical, and transverse planes. Study design: Orthodontic records of 28 patients were selected retrospectively and divided into two treatment groups. Group 1 comprised 14 patients (4 boys, 10 girls, mean age 14.2 ± 0.74 years) who had been treated with RME. Group 2 comprised 14 patients (4 boys, 10 girls, mean age 19.6 ± 2.73 years) who had been treated with SARME. Measurements were performed on lateral and posteroanterior cephalograms and dental casts obtained before (T0) and after (T1) expansion. Results: Statistically significant differences were found in soft tissue convexity angle, anterior face height, and upper nasal width in group 1, and in U1-NA length and posterior face height measurements in group 2 (P<.05). In both groups significant increases were found in interpremolar, intermolar, maxillary, and lower nasal widths and in anterior lower face height (P<.01). Statistically signifificant intergroup differences were found in the ANB angle (P<.05) and maxillary intercanine (P<.01) measurements. Conclusion: With both RME and SARME, successful expansion of maxillary dentoalveolar structures and nasal cavity and palatal widening were achieved. Sagittal plane effects of SARME were similar to those of RME on dental skeletal and airway measurements. © Medicina Oral

Silicon nanoparticle charge trapping memory cell

Cataloged from PDF version of article.A charge trapping memory with 2 nm silicon nanoparticles (Si NPs) is demonstrated. A zinc oxide (ZnO) active layer is deposited by atomic layer deposition (ALD), preceded by Al2O3 which acts as the gate, blocking and tunneling oxide. Spin coating technique is used to deposit Si NPs across the sample between Al2O3 steps. The Si nanoparticle memory exhibits a threshold voltage (V-t) shift of 2.9 V at a negative programming voltage of -10 V indicating that holes are emitted from channel to charge trapping layer. The negligible measured V-t shift without the nanoparticles and the good retention of charges (> 10 years) with Si NPs confirm that the Si NPs act as deep energy states within the bandgap of the Al2O3 layer. In order to determine the mechanism for hole emission, we study the effect of the electric field across the tunnel oxide on the magnitude and trend of the V-t shift. The Vt shift is only achieved at electric fields above 1 MV/cm. This high field indicates that tunneling is the main mechanism. More specifically, phonon-assisted tunneling (PAT) dominates at electric fields between 1.2 MV/cm 2.1 MV/cm).(C) 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

Meta-analysis of genome-wide association studies of asthma in ethnically diverse North American populations.

Asthma is a common disease with a complex risk architecture including both genetic and environmental factors. We performed a meta-analysis of North American genome-wide association studies of asthma in 5,416 individuals with asthma (cases) including individuals of European American, African American or African Caribbean, and Latino ancestry, with replication in an additional 12,649 individuals from the same ethnic groups. We identified five susceptibility loci. Four were at previously reported loci on 17q21, near IL1RL1, TSLP and IL33, but we report for the first time, to our knowledge, that these loci are associated with asthma risk in three ethnic groups. In addition, we identified a new asthma susceptibility locus at PYHIN1, with the association being specific to individuals of African descent (P = 3.9 × 10(-9)). These results suggest that some asthma susceptibility loci are robust to differences in ancestry when sufficiently large samples sizes are investigated, and that ancestry-specific associations also contribute to the complex genetic architecture of asthma

2-nm laser-synthesized Si nanoparticles for low-power charge trapping memory devices

In this work, the effect of embedding Silicon Nanoparticles (Si-NPs) in ZnO based charge trapping memory devices is studied. Si-NPs are fabricated by laser ablation of a silicon wafer in deionized water followed by sonication and filtration. The active layer of the memory was deposited by Atomic Layer Deposition (ALD) and spin coating technique was used to deliver the Si-NPs across the sample. The nanoparticles provided a good retention of charges (&gt;10 years) in the memory cells and allowed for a large threshold voltage (Vt) shift (3.4 V) at reduced programming voltages (1 V). The addition of ZnO to the charge trapping media enhanced the electric field across the tunnel oxide and allowed for larger memory window at lower operating voltages. © 2014 IEEE

Low power zinc-oxide based charge trapping memory with embedded silicon nanoparticles via Poole-Frenkel hole emission

A low power zinc-oxide (ZnO) charge trapping memory with embedded silicon (Si) nanoparticles is demonstrated. The charge trapping layer is formed by spin coating 2 nm silicon nanoparticles between Atomic Layer Deposited ZnO steps. The threshold voltage shift (ΔVt) vs. programming voltage is studied with and without the silicon nanoparticles. Applying -1 V for 5 s at the gate of the memory with nanoparticles results in a ΔVt of 3.4 V, and the memory window can be up to 8 V with an excellent retention characteristic (&gt;10 yr). Without nanoparticles, at -1 V programming voltage, the ΔVt is negligible. In order to get ΔVt of 3.4 V without nanoparticles, programming voltage in excess of 10 V is required. The negative voltage on the gate programs the memory indicating that holes are being trapped in the charge trapping layer. In addition, at 1 V the electric field across the 3.6 nm tunnel oxide is calculated to be 0.36 MV/cm, which is too small for significant tunneling. Moreover, the ΔVt vs. electric field across the tunnel oxide shows square root dependence at low fields (E 1 MV/cm) and a square dependence at higher fields (E &gt; 2.7 MV/cm). This indicates that Poole-Frenkel Effect is the main mechanism for holes emission at low fields and Phonon Assisted Tunneling at higher fields. © 2014 AIP Publishing LLC

Enhanced light scattering with energy downshifting using 16 nm indium nitride nanoparticles for improved thin-film a-Si N-i-P solar cells

In this work the effect of Indium nitride (InN) nanoparticles (NPs) on the performance of a-Si: H solar cells has been investigated. The average Jsc of InN NPs coated cells was found 6.76 mA/cm2 which is 16.69% higher than the average Jsc of the reference cell which was 5.79 mA/cm2. Average efficiency of InN NPs coated cells showed 14.16% increase from 3.32% to 3.79%. Peak EQE has increased from 44.8% at 500 nm to 51.67% at 510 nm and peak IQE has increased from 51.70% at 510 nm to 68.38% at 500 nm for InN NPs coated cell. Further study shows that EQE change is larger between 510 nm-700 nm compared to IQE change indicting a surface scattering mechanism that reduces the reflectivity. However, between 400 nm-510 nm IQE change is larger than EQE change which indicates that energy downshifting mechanism is dominating. So overall performance enhancement can be attributed to the scattering and photoluminescence properties of InN NPs that enhances absorption inside a-Si: H solar cells. © The Electrochemical Society

Effect of reactor pressure on optical and electrical properties of InN films grown by high-pressure chemical vapor deposition

The influences of reactor pressure on the stoichiometry, free carrier concentration, IR and Hall determined mobility, effective optical band edge, and optical phonon modes of HPCVD grown InN films have been analysed and are reported. The In 3d, and N 1s XPS spectra results revealed In-N and N-In bonding states as well as small concentrations of In-O and N-O bonds, respectively in all samples. InN layers grown at 1 bar were found to contain metallic indium, suggesting that the incorporation of nitrogen into the InN crystal structure was not efficient. The free carrier concentrations, as determined by Hall measurements, were found to decrease with increasing reactor pressure from 1.61×1021 to 8.87×1019 cm-3 and the room-temperature Hall mobility increased with reactor pressure from 21.01 to 155.18 cm2/Vs at 1 and 15 bar reactor pressures, respectively. IR reflectance spectra of all three (1, 8, and 15 bar) InN samples were modelled assuming two distinct layers of InN, having different free carrier concentration, IR mobility, and effective dielectric function values, related to a nucleation/interfacial region at the InN/sapphire, followed by a bulk InN layer. The effective optical band gap has been found to decrease from 1.19 to 0.95 eV with increasing reactor pressure. Improvement of the local structural quality with increasing reactor pressure has been further confirmed by Raman spectroscopy measurements. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim