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The (222) forbidden diffraction of a highly B doped high-pressure high-temperature (HPHT) diamond crystal was investigated by precise mapping using synchrotron radiation X-ray diffraction. The intensity ratios of (222) to (111) were high, ranging from 20% to 36% for the high-density dislocation areas with stacking faults (SFs), whereas the intensity ratios for the low-density dislocation areas ranged from 11% to 20%. For the high-density dislocation areas, the intensity distribution was very high in the upper region, which might correspond to the dislocation density along the X-ray path. In contrast, the intensity ratio of high-quality undoped HPHT crystals ranged from 3.0% to 4.3%, which might be due to multiple reflections of the high-quality crystal. The substrate quality can be conveniently investigated prior to device fabrication by examining the intensity of the forbidden diffraction using laboratory X-ray diffraction equipment. [ABSTRACT FROM AUTHOR]

Strong modification of the optical spectra is apparent in nitrogen-doped chemical vapor deposited (CVD) diamonds. Nitrogen-vacancy (NV) defects in CVD diamond are effectively created by nitrogen doping with a high concentration of the gaseous phase. In particular, the 575 nm center and 637 nm centers are enhanced in intensity at a N doping level of around 1018 at./cm3, while nitrogen addition during CVD growth leads to quenching of both the exciton and H3 centers. The influence of nitrogen doping on the exciton and NV defect states in a homoepitaxial CVD diamond thin film was investigated by high-resolution cathodoluminescence experiment. In addition, Raman experiments were performed to detect the internal stress. The results show that the exciton and nitrogen-related defect emission spectra underwent a shift of the peak position to a longer wavelength by nitrogen doping. The characteristic Raman peak of diamond at 1332 cm-1 showed a shift toward lower wave numbers with increasing nitrogen incorporation. [ABSTRACT FROM AUTHOR]

Presents a study which examined over-passivation films of silicon nitride and silicon dioxide on (NH[sub4])[sub2]S[subx]-treated gallium arsenide deposited by various kinds of systems with photoluminescence measurements. Influence of annealing on over-passivation; Effect of the gallium arsenide etchant before the treatment; Effect of the precleaning process with nitrogen before the deposition of silicon nitride.

Presents a study that examined the annihilation characteristics of positrons in various types of diamonds. Measurements of two-dimensional angular correlation of positron annihilation; Amount of defects in type Ib synthesized diamond; Results of the double x-ray measurements.

Background: Few quantitative studies have been conducted on the relationship between society and its languages. Individuals with autistic spectrum disorder (ASD) are known to experience social hardships, and a wide range of clinical information about their quality of life has been provided through numerous narrative analyses. However, the narratives of ASD patients have thus far been examined mainly through qualitative approaches.Objectives: In this study, we analyzed adults with ASD to quantitatively examine the relationship between language abilities and ASD severity scores.Methods: We generated phonetic transcriptions of speeches by 16 ASD adults at an ASD workshop, and divided the participants into 2 groups according to their Social Responsiveness Scale(TM), 2nd Edition (SRS(TM)-2) scores (where higher scores represent more severe ASD): Group A comprised high-scoring ASD adults (SRS(TM)-2 score: ≥ 76) and Group B comprised low- and intermediate-scoring ASD adults (SRS(TM)-2 score: < 76). Using natural language processing (NLP)-based analytical methods, the narratives were converted into numerical data according to four language ability indicators, and the relationships between the language ability scores and ASD severity scores were compared.Results and Discussion: Group A showed a marginally negative correlation with the level of Japanese word difficulty (p < .10), while the "social cognition" subscale of the SRS(TM)-2 score showed a significantly negative correlation (p < .05) with word difficulty. When comparing only male participants, Group A demonstrated a significantly lower correlation with word difficulty level than Group B (p < .10).Conclusion: Social communication was found to be strongly associated with the level of word difficulty in speech. The clinical applications of these findings may be available in the near future, and there is a need for further detailed study on language metrics designed for ASD adults. [ABSTRACT FROM AUTHOR]

A neutron bang time and burn history monitor in inertial confinement fusion with fast ignition are necessary for plasma diagnostics. In the FIREX project, however, no detector attained those capabilities because high-intensity X-rays accompanied fast electrons used for plasma heating. To solve this problem, single-crystal CVD diamond was grown and fabricated into a radiation detector. The detector, which had excellent charge transportation property, was tested to obtain a response function for intense X-rays. The applicability for neutron bang time and burn history monitor was verified experimentally. Charge collection efficiency of 99.5% ± 0.8% and 97.1% ± 1.4% for holes and electrons were obtained using 5.486 MeV alpha particles. The drift velocity at electric field which saturates charge collection efficiency was 1.1 ± 0.4 x 107 cm/s and 1.0 ± 0.3 x 107 cm/s for holes and electrons. Fast response of several ns pulse width for intense X-ray was obtained at the GEKKO XII experiment, which is sufficiently fast for ToF measurements to obtain a neutron signal separately from X-rays. Based on these results, we confirmed that the single-crystal CVD diamond detector obtained neutron signal with good S/N under ion temperature 0.5-1 keV and neutron yield of more than 109 neutrons/shot. [ABSTRACT FROM AUTHOR]

We synthesized a mosaic diamond wafer 2 in. in size (40×60mm²), which consisted of 24 single-crystal diamond (SCD) plates 10×10mm² in area, by using microwave plasma chemical vapor deposition. Even by using a cloning technique, cracking frequently occurred and the non-uniformity was remarkable for wafers that were larger than 1 in. in size. This has not been observed in smaller samples before. Appropriate crystallographic directions could avoid the cracking and is one of the predominant factors in fabricating large area SCD wafers. Comparison with numerical simulations highlighted the importance of uniformity of the substrate temperature distribution on the uniformity of the growth. [ABSTRACT FROM AUTHOR]

The performance of a diamond detector made of single-crystal diamond grown by chemical vapour deposition was studied for heavy ions, having energy of 3 MeV. Energy peaks of these low-energy ions were clearly observed. However, the pulse height for individual incident ion decreases with increasing atomic number of the ions. For understanding this pulse height reduction effect, we calculated the amount of ionizing and non-ionizing energy loss of incident ions in the diamond detector. The results of our calculation suggest the contribution of charge loss mechanisms other than the recombination effect of electron-hole pairs produced along the ionized track. We also mentioned the incomplete charge collection near the boundary region between the metal electrode and the diamond surface. [ABSTRACT FROM AUTHOR]