Cheol‐Woong Yang

Understanding the interplay between the surface structure and the passivation materials and their effects associated with surface structure modification is of fundamental importance; however, it remains an unsolved problem in the perovskite passivation field. Here, we report a surface passivation principle for efficient perovskite solar cells via a facet-dependent passivation phenomenon. The passivation process selectively occurs on facets, which is observed with various post-treatment materials

Abstract— A new empirical cooling rate indicator for metal particles is proposed. The cooling rate indicator is based on the relationship between the size of the island phase in the cloudy zone, which abuts the outer taenite rim (clear taenite I), and the cooling rate of the host meteorite as obtained by conventional metallographic techniques. The size of the island phase was measured by high‐resolution scanning electron microscopy (SEM) in 26 meteorites and decreases from 470 nm to 17 nm, while

Vertical and lateral heterogeneous structures of two-dimensional (2D) materials have paved the way for pioneering studies on the physics and applications of 2D materials. A hybridized hexagonal boron nitride (h-BN) and graphene lateral structure, a heterogeneous 2D structure, has been fabricated on single-crystal metals or metal foils by chemical vapor deposition (CVD). However, once fabricated on metals, the h-BN/graphene lateral structures require an additional transfer process for device appl

We observed graphene flakes on a SiO 2 /Si substrate and confirmed the variation in the thickness of the flakes by optical microscopy, Raman spectroscopy and scanning electron microscopy (SEM). We were able to clearly distinguish the thickness variation of the graphene provided a low primary electron acceleration voltage was used. It was found that different contrasts in SEM images at low acceleration voltages could be attributed to the fact that the generation of secondary electrons emitted fro

The size of the advanced Cu interconnects has been significantly reduced, reaching the current 7.0 nm node technology and below. With the relentless scaling-down of microelectronic devices, the advanced Cu interconnects thus requires an ultrathin and reliable diffusion barrier layer to prevent Cu diffusion into the surrounding dielectric. In this paper, amorphous carbon (a-C) layers of 0.75-2.5 nm thickness have been studied for use as copper diffusion barriers. The barrier performance and therm

Abstract Nd 2 Fe 14 B and Nd 2−x Dy x Fe 14 B (x = 0.25, 0.50) particles were prepared by the modified co-precipitation followed by reduction–diffusion process. Bright field scanning transmission electron microscope (BF-STEM) image revealed the formation of Nd–Fe–B trigonal prisms in [− 101] viewing zone axis, confirming the formation of Nd 2 Fe 14 B/Nd 2−x Dy x Fe 14 B. Accurate site for the Dy substitution in Nd 2 Fe 14 B crystal structure was determined as “f” site by using high-angle annular