Abstract. This paper demonstrates the first 4H-SiC metal-semiconductor-metal (MSM) UV photodetector. Two types of MSM photodetectors are fabricated for comparison: one in p-type 4HSiC and the other in n-type 4H-SiC. The n-type SiC photodetectors show a low dark current less than 10nA at -15V bias while the p-type ones show a lower dark current of 0.3nA at -25V. Photoresponsivity is measured fro...

A mild and convenient one-step preparation of 4H-1,3-benzoxazin-4-ones by a domino carbonylation-cyclization process is developed. Readily available ortho-iodophenols are subjected to palladium-catalyzed carbonylative coupling with Mo(CO)6 and cyanamide, followed by a spontaneous, intramolecular cyclization to afford 4H-1,3-benzoxazin-4-ones in moderate to excellent yields. Furthermore, the sco...

We report here, the results of molecular dynamics simulation of p-doped (Ga-face)GaN over n-doped (Siface)(0001)4H-SiC hetero-epitaxial material system with one-layer each of Ga-flux and (Al-face)AlN, as the interface materials, in the form of, the total Density of States (DOS). It is found that the total DOS at the Fermi-level for the heavily p-doped (Ga-face)GaN and ndoped (Si-face)4H-SiC het...

Os compostos hidrotris(2-mercaptotiazolil)borato de potássio, KMt, (1), e hidrotris(2metimazolil)borato de potássio, KTm, (2), foram preparados ao se reagir a amina tiol correspondente com KBH 4 . Foram caracterizados por métodos espectroscópicos e análise elementar. As estruturas no estado sólido de KMt.4H 2 O e do composto 2 foram determinadas por análises de difração de raios-X. A maior maci...

An experimental determination on powder mixtures of SiC-3C and 6H polytypes using an X-ray goniometer system showed the possibility of quantitative determination of polytype fraction directly from peak intensities. In combination with calculated X-ray intensities of 15R and 4H polytype, the method yields a simple equation system for the relative quantities of SiC polytypes 15R, 6H, 4H and 3C in...

Two high-yielding strategies for the synthesis of 4H-anthra[1,2-b]pyran antibiotics have been developed giving access to novel antitumor agent (ED(50) 1.5 microm) and to (S)-espicufolin (3). A key step for the assembly of the tetracyclic 4H-anthra[1,2-b]pyran-4,7,12-trione skeleton is the nucleophilic addition of an aryl lithium species onto an aldehyde which allows the introduction of either a...

The measured photomultiplication and excess noise characteristics of two 4H-SiC p-i-n diodes, with i-region widths of 0.105 μm and 0.285 μm, were modelled using a nonlocal multiplication model to determine the ionization threshold energies and the impact ionization coefficients of 4H-SiC. The modelled ionization coefficients accurately predicted the breakdown voltage of a 0.485 μm p-i-n structu...

A simple, efficient and eco-friendly procedure for the selective monohydrolysis of diethyl 2,6-dimethyl-4-aryl-4H-pyran-3,5-dicarboxylates under quaternary ammonium salt catalysis conditions is presented. The catalytic activities of various quaternary ammonium salts were investigated using different molar ratios of NaOH and water-organic solvent mixtures. The results indicate that the combinati...

Abstract Objectives: to estimate the prevalence of adolescents’ screen time in three different scenarios and possible associations with gender, sexual maturation, age group, economic class, nutritional status. Methods: a cross-sectional study conducted representative sample 3,979 adolescents from Greater Curitiba. Screen (television, computer, video game) was self-reported categorized as ≤2h/da...

In the title mol-ecule, C(19)H(20)N(2)O(2), the cyclo-hexene ring adopts a sofa conformation, while the pyran ring adopts a flattened boat conformation. In the crystal, mol-ecules are linked by N-H⋯N and N-H⋯O hydrogen bonds, forming a two-dimensional network parallel to (010).