Electrical transport and optical properties of Cd3As2 thin filmsProject supported by the National Key Research and Development Program of China (Grant Nos. 2017YFA0303302 and 2018YFA0305601) and the National Natural Science Foundation of China (Grant Nos. 61322407, 11474058, 61674040, and 11874116)

• Published in: Chinese physics B 2019-09, Vol.28 (10)
• Main Authors: Yang, Yun-Kun, Xiu, Fa-Xian, Wang, Feng-Qiu, Wang, Jun, Shi, Yi
• Format: Article
• Language: English
• Subjects: photodetectors; thin films; topological Dirac semimetals; ultra-fast optical switches
• ISSN: 1674-1056
• DOI: 10.1088/1674-1056/ab3a91

Cd3As2, as a three-dimensional (3D) topological Dirac semimetal, has attracted wide attention due to its unique physical properties originating from the 3D massless Dirac fermions. While many efforts have been devoted to the exploration of novel physical phenomena such as chiral anomaly and phase transitions by using bulk crystals, the development of high-quality and large-scale thin films becomes necessary for practical electronic and optical applications. Here, we report our recent progress in developing single-crystalline thin films with improved quality and their optical devices including Cd3As2-based heterojunctions and ultrafast optical switches. We find that a post-annealing process can significantly enhance the crystallinity of Cd3As2 in both intrinsic and Zn-doped thin films. With excellent characteristics of high mobility and linear band dispersion, Cd3As2 exhibits a good optical response in the visible-to-mid-infrared range due to an advantageous optical absorption, which is reminiscent of 3D graphene. It also behaves as an excellent saturable absorber in the mid-infrared regime. Through the delicate doping process in this material system, it may further open up the long-sought parameter space crucial for the development of compact and high-performance mid-infrared ultrafast sources.