摘要
使用射频磁控溅射技术制备了钼(Mo)膜,再利用硒化退火方式生成二硒化钼(MoSe2)薄膜.对MoSe2薄膜的表面形貌、晶体结构和光学带隙进行了表征和分析.结果显示,MoSe2薄膜的晶体结构与硒化温度(Ts)密切相关,随着硒化温度的升高,薄膜的平均晶粒尺寸先略减小后增大,且(002)晶面取向优先生长.MoSe2薄膜对短波长光(600 nm左右)具有较低的吸收率.随着硒化温度升高,MoSe2的直接带隙波发生蓝移,光学带隙随之减小.研究表明,通过改变硒化温度可以有效调控MoSe2结构和光学带隙,为MoSe2薄膜在光学器件应用方面提供更多可能.
Abstract
In recent years,MoSe2,as a kind of transition metal dichalcogenide,has aroused widespread research interest due to its special crystal structure with different electrical and optical properties.The band gap of molybdenum diselenide can be manipulated by different layers,strain engineering,doping,or the formation of heterostructures,which makes it potential advantages in optoelectronic devices and photovoltaic applications.In this work,we investigate the influence of selenization temperature on the structures and optical properties of the MoSe2 films.Molybdenum(Mo)thin films are prepared by RF magnetron sputtering,and then MoSe2 thin films are generated by selenization annealing.The surface morphology,crystal structure,and optical bandgap for each of the MoSe2 thin films are characterized and analyzed by using scanning electron microscopy,X-ray diffraction,and ultraviolet visible spectroscopy,respectively.The results show that the crystal structures of the MoSe2 thin films are closely related to the selenization temperature(Ts):with the increase of selenization temperature,the average grain size in the thin film decreases slightly and then increases rapidly from 24.82 nm to 55.76 nm.Meanwhile,the(002)crystal plane of MoSe2 also exhibits preferential growth with temperature increasing.Each MoSe2 thin film has a low absorption rate for short-wavelength light(around 600 nm).With the increase of selenization temperature,the bandgap waves of the MoSe2 thin films are blue-shifted,and the optical bandgaps decrease,which is attributed to the fact that different selenization temperatures cause the lattice size of MoSe2 to change,thereby affecting the spatial expansion of its electronic wave function.In addition,the structure and optical bandgap of MoSe2 can be effectively controlled by changing the selenization temperature,which provides more possibilities for the applications of the MoSe2 thin films in optical devices.
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