Large Area Epitaxial Lateral Overgrowth of Semipolar (1(Formula Presented)01) GaN Stripes on Patterned Si Substrates Prepared using Maskless Lithography

Takeda N., Uemukai M., Tanikawa T., et al. Large Area Epitaxial Lateral Overgrowth of Semipolar (1(Formula Presented)01) GaN Stripes on Patterned Si Substrates Prepared using Maskless Lithography. Physica Status Solidi (B) Basic Research , (2024); https://doi.org/10.1002/pssb.202400071.Selective area growth and epitaxial lateral overgrowth (ELOG) of semipolar (1 (Formula presented.) 01) GaN stripes are demonstrated on a trench patterned vicinal (001) Si substrate fabricated by a maskless photolithography-based process. High precision alignment enables selective mask formation to one sidewall of the trench. Selective area growth of GaN stripes is conducted from the (111) plane sidewall of Si, and ELOG region reaches ≈13 μm. The ELOG GaN crystal is dislocation-free at most areas. The semipolar GaN stripes with atomically flat surface morphology are uniformly obtained. Light-emitting diode structures with InGaN/GaN multiple quantum wells are grown on the 13-μm ELOG (1 (Formula presented.) 01) GaN stripes and a single photoluminescence emission peaked at 485 nm is obtained, suggesting potential for the cost-effective semipolar micro light-emitting diode fabrication technologies

Metalorganic Vapor-Phase Epitaxy of +c/−c GaN Polarity Inverted Bilayer for Transverse Quasi-Phase-Matched Wavelength Conversion Device

Ikeda K., Malik S., Uemukai M., et al. Metalorganic Vapor-Phase Epitaxy of +c/−c GaN Polarity Inverted Bilayer for Transverse Quasi-Phase-Matched Wavelength Conversion Device. Physica Status Solidi (B) Basic Research, (2024); https://doi.org/10.1002/pssb.202400161.Photon-pair generation based on optical parametric down-conversion has attracted for the application as a light source for quantum information. Highly efficient wavelength-conversion devices require a polarity-inversion structure when using nitride semiconductors. A transverse quasi-phase-matching (QPM) polarity-inverted GaN bilayer channel waveguide device is suitable for efficient wavelength conversion. This study designed a cross-section device to satisfy the modal dispersion phase-matching condition between the TM₀₂ mode pump light and the TM₀₀ mode signal/idler light. Moreover, an AlN oxidation interlayer fabricates the Ga-polar/N-polar (+c/−c) GaN layers via metalorganic vapor-phase epitaxy (MOVPE). A 145 nm thick film layer with a macro-step-free surface is grown by optimizing the −c-GaN growth conditions and reducing the substrate off-angle to 0.2°. Next, the AlN layer is oxidized in an electric furnace and MOVPE is used to regrow a 1500 nm thick +c-GaN layer. A macrosteps-free surface can be achieved by reducing the off-angle to 0.2° and optimizing the −c-GaN growth conditions to avoid hillock formation. These results pave the way for improving the efficiency of GaN transverse QPM wavelength-conversion devices

Effect of Growth Pressure on Structural Properties of SiC Film Grown on Insulator by Utilizing Graphene as a Buffer Layer

Heteroepitaxial growth of silicon carbide (SiC) on graphene/SiO2/Si substrates was carried out using a home-made hot-mesh chemical vapor deposition (HM-CVD) apparatus. Monomethylsilane (MMS) was used as single source gas while hydrogen (H2) as carrier gas. The substrate temperature, tungsten mesh temperature, H2 flow rate and distance between mesh and substrate were fixed at 750 °C, 1700 °C, 100 sccm and 30 mm, respectively. The growth pressures were set to 1.2, 1.8 and 2.4 Torr. The growth of 3C-SiC (111) on graphene/SiO2/Si were confirmed by the observation of θ-2θ diffraction peak at 35.68°. The diffraction peak of thin film on graphene/SiO2/Si substrate at pressure growth is 1.8 Torr is relatively more intense and sharper than thin film grown at pressure growth 1.2 and 2.4 Torr, thus indicates that the quality of grown film at 1.8 Torr is better. The sharp and strong peak at 33° was observed on the all film grown, that peak was attributed Si(200) nanocrystal. The reason why Si (200) nanocrystal layer is formed is not understood. In principle, it can’t be denied that the low quality of the grown thin film is influenced by the capability of our home-made apparatus. However, we believe that the quality can be further increased by the improvement of apparatus design. As a conclusion, the growth pressures around 1.8 Torr seems to be the best pressures for the growth of heteroepitaxial 3C-SiC thin film

積雪-海氷系の放射伝達モデルの開発

第6回極域科学シンポジウム[OM] 極域気水圏11月16日（月）　国立極地研究所１階交流アトリウ

Satellite-derived snow grain size over the Greenland Ice Sheet and its relationships with climate indices

The Tenth Symposium on Polar Science/Ordinary sessions: [OM] Polar Meteorology and Glaciology, Wed. 4 Dec. / 2F Auditorium, National Institute of Polar Researc

Fatal case of subdural empyema caused by Campylobacter rectus and Slackia exigua

We report a fatal subdural empyema caused by Campylobacter rectus in a 66-year-old female who developed acute onset of confusion, dysarthria, and paresis in her left extremities. A CT scan showed hypodensity in a crescentic formation with a mild mid-line shift. She had a bruise on her forehead caused by a fall several days before admission, which initially raised subdural hematoma (SDH) diagnosis, and a burr hole procedure was planned. However, her condition deteriorated on the admission night, and she died before dawn. An autopsy revealed that she had subdural empyema (SDE) caused by Campylobacter rectus and Slackia exigua. Both microorganisms are oral microorganisms that rarely cause extra-oral infection. In our case, head trauma caused a skull bone fracture, and sinus infection might have expanded to the subdural space causing SDE. CT/MRI findings were not typical for either SDH or SDE. Early recognition of subdural empyema and prompt initiation of treatment with antibiotics and surgical drainage is essential for cases of SDE. We present our case and a review of four reported cases

Safety and Complications of Medical Thoracoscopy

Objectives. To highlight the possible complications of medical thoracoscopy (MT) and how to avoid them. Methods. A retrospective and prospective analysis of 127 patients undergoing MT in Nagoya Medical Center (NMC) and Toyota Kosei Hospital. The data about complications was obtained from the patients, notes on the computer system, and radiographs. Results. The median age was 71.0 (range, 33.0–92.0) years and 101 (79.5%) were males. The median time with chest drain after procedure was 7.0 (range, 0.0–47.0) days and cases with talc poudrage were 30 (23.6%). Malignant histology was reported in 69 (54.3%), including primary lung cancer in 35 (27.5), mesothelioma in 18 (14.2), and metastasis in 16 (12.6). 58 (45.7%) revealed benign pleural diseases and TB was diagnosed in 15 (11.8%). 21 (16.5%) patients suffered from complications including lung laceration in 3 (2.4%), fever in 5 (3.9%) (due to hospital acquired infection (HAI) in 2, talc poudrage in 2, and malignancy in 1), HAI in 2 (1.6%), prolonged air-leak in 14 (11.0%), and subcutaneous emphysema in 1 (0.8%). Conclusions. MT is generally a safe procedure. Lung laceration is the most serious complication and should be managed well. HAI is of low risk and can be controlled by medical treatment

Darkening of Greenland ice sheet and satellite-derived snow parameters

第6回極域科学シンポジウム分野横断セッション：[IA] 急変する北極気候システム及びその全球的な影響の総合的解明―GRENE北極気候変動研究事業研究成果報告2015―11月19日（木）　国立極地研究所 2階 大会議

Reanalysis of the long-term trend of JASMES snow cover extent in the Northern Hemisphere

第6回極域科学シンポジウム分野横断セッション：[IA] 急変する北極気候システム及びその全球的な影響の総合的解明―GRENE北極気候変動研究事業研究成果報告2015―11月19日（木）　国立極地研究所 2階 大会議