The 262nd MANA & the 113th ICYS Joint Seminar
Dr. Liwen Sang & Dr. Jianhua Gao
| Date | May 18, Friday |
| Time | 15:30-16:30 |
| Place | Auditorium, 1F, WPI - MANA Bldg., NAMIKI Site, NIMS |
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15:30-16:00
Photoelectrical energy-conversion devices based on III-Nitrde semiconductors
III-Nitride semiconductors including GaN, InN, AlN and their ternary and quarternary alloys exhibit the widest direct bandgaps among all the semiconductors, from near infrared (InN at 0.65 eV) to deep ultraviolet (UV) range (AlN at 6.2 eV). This unique property provides them the promising applications in the high-efficiency photoelectrical energy conversion devices. In this presentation, we report on the high-performance visible-blind photodiodes and solar cells fabricated using the III-Nitride ternary alloy InGaN film. The photodiodes showed the highest UV/Visible discrimination ratio of more than 106, which is superior to other materials. The InGaN-based solar cells also demonstrated the potential toward a high conversion efficiency.
Speaker
Dr. Liwen Sang, ICYS-MANA Researcher, NIMS
Chair
Dr. Kenjiro Miyano, Managing Director, ICYS, NIMS
16:00-16:30
Growth of Single-layer Graphene and Hexagonal Boron Nitride on Metal Substrates
The typical sp2–bonded two dimensional materials such as graphene and hexagonal boron nitride (h-BN) layer with honeycomb crystal structure, have attracted special interests in both fundamental research and potential applications because of their remarkable properties and chemical stability. High quality graphene and h-BN layers can provide new opportunities in potential applications, however, the large scale fabrication of graphene and h-BN with large percentage of single layer is still a challenge. Therefore, synthesis of single-layer graphene and h-BN is highly desirable. Here we report the fabrication of single-layer graphene on carbon-doped single-crystal Pt(111) (0.05 %) substrate. It is found that single-layer graphene islands can form on Pt(111) surfaces, the size can be up to about 50µm. The atomic structure of graphene islands has been investigated by scanning tunneling microscopy (STM), which exhibit hexagonal atomic lattice, indicating the weak interaction between graphene and the Pt(111) substrate. Secondly, we synthesized the single-layer and few-layer h-BN on Fe-Cr-Ni alloy by surface segregation. We found that the triangular shape of h-BN flakes can be formed. The present synthesis can provides a novel technique for atomically graphene and h-BN layer fabrication.
Speaker
Dr. Jianhua Gao, ICYS-Sengen Researcher, NIMS
Chair
Dr. Yasushi Yamauchi, Group Leader, Spin Characterization Group, Nano Characterization Unit, NIMS