Kistner-Morris Jed, Shi Ao, Liu Erfu, Arp Trevor, Farahmand Farima, Taniguchi Takashi, Watanabe Kenji, Aji Vivek, Lui Chun Hung, Gabor Nathaniel
Department of Physics and Astronomy, University of California, Riverside, CA, 92521, USA.
National Laboratory of Solid State Microstructures, School of Physics, and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, 210093, China.
Nat Commun. 2024 May 14;15(1):4075. doi: 10.1038/s41467-024-48321-1.
Semiconductor heterojunctions are ubiquitous components of modern electronics. Their properties depend crucially on the band alignment at the interface, which may exhibit straddling gap (type-I), staggered gap (type-II) or broken gap (type-III). The distinct characteristics and applications associated with each alignment make it highly desirable to switch between them within a single material. Here we demonstrate an electrically tunable transition between type-I and type-II band alignments in MoSe/WS heterobilayers by investigating their luminescence and photocurrent characteristics. In their intrinsic state, these heterobilayers exhibit a type-I band alignment, resulting in the dominant intralayer exciton luminescence from MoSe. However, the application of a strong interlayer electric field induces a transition to a type-II band alignment, leading to pronounced interlayer exciton luminescence. Furthermore, the formation of the interlayer exciton state traps free carriers at the interface, leading to the suppression of interlayer photocurrent and highly nonlinear photocurrent-voltage characteristics. This breakthrough in electrical band alignment control, interlayer exciton manipulation, and carrier trapping heralds a new era of versatile optical and (opto)electronic devices composed of van der Waals heterostructures.
半导体异质结是现代电子学中无处不在的组件。它们的特性关键取决于界面处的能带排列，这种排列可能呈现跨带隙（I型）、交错带隙（II型）或破裂带隙（III型）。与每种排列相关的独特特性和应用使得在单一材料内实现它们之间的切换非常有必要。在此，我们通过研究MoSe₂/WS₂异质双层的发光和光电流特性，展示了I型和II型能带排列之间的电可调转变。在其本征状态下，这些异质双层呈现I型能带排列，导致来自MoSe₂的主导层内激子发光。然而，施加强层间电场会诱导转变为II型能带排列，从而产生明显的层间激子发光。此外，层间激子态的形成在界面处捕获自由载流子，导致层间光电流的抑制和高度非线性的光电流-电压特性。这种在能带排列控制、层间激子操纵和载流子捕获方面的突破预示着由范德华异质结构组成的多功能光学和（光）电子器件的新时代。
