With a new polycarbonate-film-based dry transfer method, we successfully fabricated twisted stacked black phosphorus. Optical characterization showed the overlapping area had special optical response, and high-frequency Raman spectroscopy showed unexpected blue shifts in Ag 1 and Ag 2 modes. Density functional theory (DFT) calculations confirmed these blue shifts in twisted bilayer black phosphorus, and revealed significant interlayer coupling effects. Charge distribution calculations indicated other interactions beyond van der Waals force may exist in twisted bilayer black phosphorus. This finding may cast some insight on phonon modulation effect and give some potential applications such as optical filters and infrared photodetectors.

No abstract

No abstract

Abstract:In this work, a series of quaternary Al x In y Ga 1−x−y N thin films have been successfully achieved using metal organic chemical vapor deposition (MOCVD) method with adjustable trimethylaluminum (TMA) flows. Surface morphology and optical properties of Al x In y Ga 1−x−y N films have been evaluated. The indium segregation effect on the enhancement of UV luminescence emission in Al x In y Ga 1-x-y N films with increasing TMA flows was investigated. Our results shed some lights on future optical materials design and LED/LD applications.

No abstract