42820 research outputs found
Sort by
Hydrogen and point defect introduction into 4H-SiC by plasma treatment
No full textThis study investigates the effect of hydrogen plasma treatment (HPT) on defect introduction and carrier lifetime in SiC. Secondary ion mass spectrometry shows increased hydrogen diffusion at higher HPT temperatures and complete hydrogen release after annealing. Microwave photoconductivity decay measurements show reduced carrier lifetime after HPT, which partially recovers after annealing but remains lower than that of non-HPT-treated samples. Deep level transient spectroscopy observes point defects introduced by HPT, and they remain even after annealing at 1600 °C. Therefore, HPT is a scalable, cost-effective approach to induce point defects for mitigating bipolar degradation and improve SiC device reliability through defect engineering and carrier lifetime control.journal articl
Humidity-independent acetone gas sensors with ppbv-level sensitivity and high selectivity, using an In2O3 microporous nanoneedle array
No full textThe detection of ppbv-level acetone is critical for the non-invasive diagnosis of diabetes and assessment of metabolic conditions. Highly sensitive humidity-independent gas sensors are required to achieve this goal. However, conventional semiconductor metal oxide (SMO) sensors often exhibit reduced performance in humid air. To overcome these limitations, we synthesized an In2O3 microporous nanoneedle array via chemical bath deposition and thermal treatment. These nanoneedles, composed of 3.4 ± 0.8 nm nanocrystallites, were meticulously arranged into well-ordered nanorods. The array featured pores with a diameter of 1.78 nm and exhibited both cubic and hexagonal phases of In2O3. The nanoneedles were formed through heterogeneous nucleation on the alumina substrate, followed by vertical and lateral growth, which produced self-standing porous structures with increasing size over the deposition time. The In2O3 microporous nanoneedle array sensors demonstrated exceptional sensitivity to acetone among 7 VOC gases, achieving a noteworthy response (Ra·Rg−1 = 8.17 at 100 ppbv). The experimental and theoretical limits of detection (LOD) for acetone in dry air were 5 ppbv and 152 pptv, respectively. Notably, the sensor maintained an experimental LOD of 10 ppbv for acetone at 90% relative humidity (Ra·Rg−1 = 2.98 at 10 ppbv). Moreover, the sensors exhibited excellent reproducibility, fast response/recovery times, and good long-term stability. Appropriate control of the nanostructure morphology contributes to achieving humidity-independent acetone sensing without the need for hybrid materials or noble metal catalysts. This approach provides a practical and reliable strategy for acetone sensing in humid atmospheres, supporting early diabetes screening and monitoring of metabolic conditions.journal articl
Synthesis of 2,6-diazabicyclo[3.3.1]nonanes via intramolecular cycloaddition of nitrones
No full textA new synthesis route to 2,6-diazabicyclo[3.3.1]nonanes as a scaffold of conformationally restricted diamines is disclosed. Starting from 4-amino-1-Boc-piperidine (Boc = tert-butoxycarbonyl), introduction of an alkene unit on the 4-amino group, followed by removal of the Boc group, afforded secondary amines. Subsequent oxidation of the amines with Oxone furnished nitrones, which underwent intramolecular cycloaddition to construct the 2,6-diazabicyclo[3.3.1]nonane skeleton.journal articl
Development of numerical model of moving bed CO2 capture process using amine-impregnated solid adsorbent
Get PDFdoctoral thesi
