Prof. Wu Yanqing Made Headway in New 2D Semiconductor
On March 10th, a paper titled Broadband Black-Phosphorus Photodetectors with High Responsivity produced by research group led by Prof. Wu Yanqing, a“Thousand Young Talents” scholar from Wuhan National High Magnetic Field Center, was published online by Advanced Materials (IF 17.493, DOI: 10.1002/adma.201506352), a top international journal.
Black Phosphorus is a novel two dimensional (2D) material discovered in recent years with a direct bandgap and high-mobility, which makes it an appealing candidate for future application in electronic and optoelectronic devices. In present work, we fabricated Black Phosphorus field-effect transistors (BP FETs) via nanofabrication, these devices have different channel lengths among which the minimum length reaches 100 nm. Our research has shown that the photoresponsivity of BP FET is in inverse proportion to square of the channel length, a 100 nm device shows a record-high responsivity at room temperature. Upon illumination of laser light with a wavelength of 633 nm, the BP FET with 100 nm channel length shows a photoresponsivity reaching 4.3×106 A/W, which is the highest responsivity of BP FETs all around the globe. Also, these performance parameters are among the best in the 2D materials-based photodetectors reported so far. Contrasting with other photodetectors, the BP FETs can demonstrate high responsivity in a broadband spectral range. For example, the photoresponsivity reaches above 103 A/W when illuminated with 900 nm near-infrared laser light. In addition, for the first time, we carried out a low-temperature detection with BP FETs and a systematic analysis for the significant improvement in responsivity and quantum efficiency contrasting with those at room temperature. The first author in this paper is doctoral student Huang Mingqiang from School of Physics in 2013 grade.
In addition, on February 14th, another paper produced by the research group led by Prof. Wu Qingyan was published online by Nanoscale (DOI: .1039/C5NR06647F）, a journal affiliated to Royal Society of Chemistry, which is titled Mechanisms of current fluctuation in ambipolar black phosphorus field-effect transistors. In this work, we conducted our research on the electronic transport and noise mechanism of ambipolar black phosphorus field-effect transistors (ambipolar BP FET) at different temperatures. The results show that BP FET exhibits clear ambipolar behavior, i.e., the dominated noise mechanism of the BP pFETs is carrier number, while the one of BP nFETs is mobility fluctuation. This means significantly on both theory and practice for furthering the development and application of layered BP semiconductor.
The above scientific research work is funded by Thousand Talents Plan initialed by the Organization Department of the Central Committee of the CPC, National Natural Science Foundation of China, Huazhong University of Science and Technology, etc.