Wang Yadong, Iyikanat Fadil, Rostami Habib, Bai Xueyin, Hu Xuerong, Das Susobhan, Dai Yunyun, Du Luojun, Zhang Yi, Li Shisheng, Lipsanen Harri, García de Abajo F Javier, Sun Zhipei
Department of Electronics and Nanoengineering, Aalto University, Espoo, 02150, Finland.
ICFO-Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, Castelldefels, Barcelona, 08860, Spain.
Adv Mater. 2022 Jan;34(3):e2107104. doi: 10.1002/adma.202107104. Epub 2021 Nov 23.
Electronic states and their dynamics are of critical importance for electronic and optoelectronic applications. Here, various relevant electronic states in monolayer MoS , such as multiple excitonic Rydberg states and free-particle energy bands are probed with a high relative contrast of up to ≥200 via broadband (from ≈1.79 to 3.10 eV) static third-harmonic spectroscopy (THS), which is further supported by theoretical calculations. Moreover, transient THS is introduced to demonstrate that third-harmonic generation can be all-optically modulated with a modulation depth exceeding ≈94% at ≈2.18 eV, providing direct evidence of dominant carrier relaxation processes associated with carrier-exciton and carrier-phonon interactions. The results indicate that static and transient THS are not only promising techniques for the characterization of monolayer semiconductors and their heterostructures, but also a potential platform for disruptive photonic and optoelectronic applications, including all-optical modulation and imaging.
电子态及其动力学对于电子和光电子应用至关重要。在此，通过宽带（约1.79至3.10 eV）静态三次谐波光谱（THS），以高达≥200的高相对对比度探测了单层MoS₂中的各种相关电子态，如多个激子里德堡态和自由粒子能带，理论计算进一步支持了这一结果。此外，引入瞬态THS以证明在约2.18 eV处三次谐波产生可以通过全光调制，调制深度超过约94%，这为与载流子 - 激子和载流子 - 声子相互作用相关的主导载流子弛豫过程提供了直接证据。结果表明，静态和瞬态THS不仅是表征单层半导体及其异质结构的有前途的技术，而且是用于包括全光调制和成像在内的颠覆性光子和光电子应用的潜在平台。
