This article shows that replacing hydrogen with deuterium improves the quality of microwave plasma-assisted chemical vapor deposition homoepitaxial diamond. Suppression of point defects in the bulk and of nonepitaxial crystallites and increasing of free-exciton emission intensity were revealed by electron paramagnetic resonance, optical microscopy, and cathodoluminescence, respectively. The isotope effects on the etching rate of diamond by deuterium are also revealed. The isotope effects are discussed from the viewpoint of etching effects.

Cathodoluminescence (CL) properties of various kinds of organic material were investigated for the purpose of staining biological specimens and obtaining CL images. Several kinds of organic light emitting device (OLED) material exhibited CL. The europium complex, Eu(dbm)3(phen), showed the strongest CL signal and was chemically modified for biological staining. However, the CL intensity from the stained biological specimen was too weak to build CL images. We discussed the CL properties of organic materials considering their chemical structure and charge distribution in the molecules.

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Hydrogen-vacancy related defect (H1′) in chemical vapor deposition homoepitaxial diamond films has been investigated by electron paramagnetic resonance and cathodoluminescence. It is found that the concentration of H1′ significantly decreases as the dilution (CH4∕H2) ratio decreases. It is also confirmed that the intensity of free-exciton emission (Iex) increases as the CH4∕H2 ratio decreases. The complementary relationship between Iex and H1′ can be explained by considering that H1′ acts as a nonradiative recombination center which reduces the lifetime of free exciton and Iex. The suppression mechanism of H1′ is discussed by considering the balance between the growth rate and the annihilation rate of H1′ in the subsurface region.

Reduction of threading dislocation density in SiGe layers on Si (001) using a two-step strain-relaxation procedure Appl.