分子束外延
薄膜
材料科学
异质结
激子
光电子学
半导体
带隙
结晶度
吸收边
吸收(声学)
衰减系数
铋
外延
光学
纳米技术
图层(电子)
凝聚态物理
复合材料
冶金
物理
作者
Takahiro Yasunami,Masao Nakamura,Soichi Inagaki,S. Toyoda,Norio Ogawa,Y. Tokura,Masashi Kawasaki
摘要
Bismuth triiodide (BiI3) is a two-dimensional (2D) layered semiconductor with a fairly narrow bandgap (∼2 eV) and strong excitonic absorption near the band edge. Being endowed with a large absorption coefficient in the visible range, BiI3 attracts a growing interest as a potential compound for thin-film optoelectronic devices. Although various growth techniques have been employed so far, thin films with a high enough crystallinity for the solid assignment of the exciton resonances have never been synthesized. Here, we demonstrate molecular beam epitaxy of high-quality BiI3 films by employing a thin buffer layer deposited at a low temperature (30 °C) to make high temperature (70 °C) growth possible. The films fabricated by this two-step method realize a single-crystalline structure and atomically flat surfaces. The absorption spectra of the films exhibit strong and sharp excitonic resonances near the band edge, indicating the high crystallinity of the films comparable to the bulk single crystals. The presently established fabrication process should be widely applicable to other 2D halide thin films and heterostructures, providing ideal platforms for observing unprecedented emergent phenomena.
科研通智能强力驱动
Strongly Powered by AbleSci AI