Zinc-based nitride CaZn 2 N 2 films grown by molecular beam epitaxy (MBE) with a plasmaassisted active nitrogen-radical source are promising candidates of next-generation semiconductors for light-emitting diodes and solar cells. This nitride compound has previously only been synthesized in a bulk form by ultrahigh-pressure synthesis at 5 GPa. Three key factors have been found to enable heteroepitaxial film growth: (i) precise tuning of the individual flux rates of Ca and Zn, (ii) the use of GaN template layers on sapphire c-plane as substrates, and (iii) the application of MBE with an active N-radical source. Because other attempts at physical vapor deposition and thermal annealing processes have not produced CaZn 2 N 2 films of any phase, this rf-plasma-assisted MBE technique represents a promising way to stabilize CaZn 2 N 2 epitaxial films. The estimated optical band gap is ~1.9 eV, which is consistent with the value obtained from bulk samples. By unintentional carrier doping, n-and p-type electronic conductions are attained with low carrier densities of the order of 10 13 cm −3 . These features represent clear advantages when compared with Zn-based oxide semiconductors, which usually have much higher carrier densities irrespective of their intentionally undoped state. The carrier mobilities at room temperature are 4.3 cm 2 /(V·s) for electrons and 0.3 cm 2 /(V·s) for hole carriers, which indicates that transport properties are limited by grain boundary scattering, mainly because of the low-temperature growth at 250 °C, which realizes a high nitrogen chemical potential.
This paper aims to examine students' reaction to an achievement English test, focusing on strategy changes after the test. The 4 th year students (aged 18−19) in National Institute of Technology answered questionnaire after an English midterm examination. By comparing the results of two groups (high / low proficiency group) , it was found that high proficiency group inclined toward memory strategy more than low proficiency group did.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.