Nishikubo Ryosuke, Saeki Akinori
Department of Applied Chemistry, Graduate School of Engineering , Osaka University , 2-1 Yamadaoka , Suita , Osaka 565-0871 , Japan.
Precursory Research for Embryonic Science and Technology (PRESTO) , Japan Science and Technology Agency , 4-1-8 Honcho , Kawaguchi , Saitama 332-0012 , Japan.
J Phys Chem Lett. 2018 Sep 20;9(18):5392-5399. doi: 10.1021/acs.jpclett.8b02218. Epub 2018 Sep 5.
Bismuth sulfide (BiS) is an attractive 2D layered, visible-light-absorbing semiconductor composed of nontoxic, abundant elements. Improving the quality of a BiS film for device applications while maintaining its intrinsic electronic properties is a challenge, as conventional film fabrication processes require a trade-off due to the uncontrolled nucleation and growth steps. We report a novel procedure for BiS film formation involving spin-coating of a precursor solution of bismuth acetate and thiourea, followed by crystallization under diluted HS gas. This two-step process produced a large-grained (<400 nm), smooth (surface roughness = 1.7 nm), and highly pure BiS film with a layer-stacked structure on a substrate. Most importantly, the film exhibited a moderate Hall effect electron mobility (∼7 cm V s) and excellent performance as a photoresistor with improved photoconductance and on-off ratio compared with those prepared by conventional methods. Our approach provides a versatile route for the development of metal sulfide semiconductors for optoelectronic devices.
硫化铋（BiS）是一种具有吸引力的二维层状可见光吸收半导体，由无毒且储量丰富的元素组成。在保持其固有电子特性的同时提高用于器件应用的BiS薄膜质量是一项挑战，因为传统的薄膜制造工艺由于成核和生长步骤不受控制而需要进行权衡。我们报道了一种形成BiS薄膜的新方法，该方法包括旋涂醋酸铋和硫脲的前驱体溶液，然后在稀释的HS气体下结晶。这个两步过程在基板上产生了大晶粒（<400 nm）、光滑（表面粗糙度 = 1.7 nm）且高度纯净的具有层状堆叠结构的BiS薄膜。最重要的是，与通过传统方法制备的薄膜相比，该薄膜表现出适度的霍尔效应电子迁移率（~7 cm² V⁻¹ s⁻¹）以及作为光阻器的优异性能，具有改善的光电导和开/关比。我们的方法为开发用于光电器件的金属硫化物半导体提供了一条通用途径。
