材料科学
无定形固体
椭圆偏振法
超晶格
折射率
光电子学
摩尔吸收率
吸收(声学)
衰减系数
分子束外延
光学
薄膜
蒸发
图层(电子)
外延
纳米技术
化学
结晶学
物理
复合材料
热力学
作者
Joshua D. John,Shun Okano,Apoorva Sharma,S. Nishimoto,Noritoshi Miyachi,Kunitaka Enomoto,Jun Ochiai,Ichitaro Saito,Georgeta Salvan,Tomoaki Masuzawa,Takatoshi Yamada,Daniel H. C. Chua,Dietrich R. T. Zahn,Ken Okano
标识
DOI:10.1088/1361-6463/abf228
摘要
Abstract Superlattice structures have a variety of electrical and optical properties that allow for interesting applications like quantum cascade lasers and ultrasensitive photo-detectors. However, such structures require high-tech fabrication methods like molecular beam epitaxy, and this technology barrier means that these promising devices are not in widespread use. Using the simple method of rotational evaporation, we fabricated films with alternating multi-nanolayers of amorphous selenium (Se) and arsenic selenide (As 2 Se 3 ). We investigated the optical properties of the individual materials, and the resulting multi-layer structure using spectroscopic ellipsometry. The results were modeled using Cody–Lorentz oscillators to obtain the refractive index ( n ) and extinction coefficient ( k ). The models showed the optical band gaps of Se and As 2 Se 3 to be 1.97 and 1.69 eV, respectively. The absorption coefficient ( α ) of the multi-layer structure showed a series of five ‘steps’ in energy at 1.72, 1.82, 1.89, 1.97, and 2.04 eV. These are confirmed to stem from the transitions between confined quantum well levels due to the superlattice structure. In this way, the optical measurement using spectroscopic ellipsometry confirms the possibility of fabricating good quality nanostructutres using amorphous materials and rotational evaporation.
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