We investigate fundamental issues on the growth of GaAs/GaAsN core–shell heterostructure nanowires (NWs) by plasma-assisted molecular beam epitaxy. A Ga catalyst crystallizes during growth interruption at a high As pressure, and afterwards the growth dominantly progresses mainly increasing the NW diameter, thereby forming a wire shell. The shell diameter increases linearly depending on growth time and group III flux, similarly to the growth mechanism of planar layers. The lateral growth rate is 0.19 times lower than the growth rate of planar GaAs on a (100) substrate. At a substrate temperature 570 °C, nitrogen incorporation is inefficient in the shell layer. At a substrate temperature of 430 °C, the nitrogen is effectively introduced under continuous plasma irradiation during the growth of the GaAsN shell, resulting in the introduction of nitrogen within the shell estimated up to about 0.5%.
It is believed that the functional properties of the protein are dependent on its structure. Therefore, it is critical to predict the protein's structure to understand the functional properties. One of the most widely studied protein structure prediction models is the hydrophobic-hydrophilic (HP) model, which abstracts the dominant force in protein folding. That is, to explain the hydrophobic interaction, the HP model tries to maximize the number of contacts among hydrophobic amino acids. Although a number of heuristics have been proposed to find a tight lower bound for the number of contacts, these methods cannot guarantee the quality of the obtained solution since no information on upper bound has been obtained. In this research, we focus on identifying the efficiently computable upper bound. We present a new mathematical formulation of the HP model, which can provide an upper bound using linear relaxation of the formulation. Computational experiments using benchmark problems show that our formulation provides tight upper bound.
We have investigated the selective area growth of InP on nano-patterned Si substrates with SiO 2 mask by molecular beam epitaxy. By optimizing the growth conditions, the growth of one separate InP single crystallite for each Si opening has been accomplished. It is found that when single crystallites coalesced into larger grains beyond Si openings, lattice strains were introduced in the grains because of the difference in thermal expansion coefficient between Si and InP. This clearly shows that the growth of one InP single crystallite for each Si opening is indispensable for growing stress-and defect-free InP regions on SiO 2 towards the application to next generation MOSFETs as the channel materials.
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.