Kumar Sunil, Singh Arvind, Kumar Sandeep, Nivedan Anand, Tondusson Marc, Degert Jérôme, Oberlé Jean, Yun Seok Joon, Lee Young Hee, Freysz Eric
Opt Express. 2021 Feb 1;29(3):4181-4190. doi: 10.1364/OE.412548.
THz conductivity of large area MoS and MoSe monolayers as well as their vertical heterostructure, MoSeMoS is measured in the 0.3-5 THz frequency range. Compared to the monolayers, the ultrafast THz reflectivity of the MoSeMoS heterobilayer is enhanced many folds when optically excited above the direct band gap energies of the constituting monolayers. The free carriers generated in the heterobilayer evolve with the characteristic times found in each of the two monolayers. Surprisingly, the same enhancement is recorded in the ultrafst THz reflectivity of the heterobilayer when excited below the MoS bandgap energy. A mechanism accounting for these observations is proposed.
测量了大面积MoS和MoSe单层及其垂直异质结构MoSeMoS在0.3-5太赫兹频率范围内的太赫兹电导率。与单层相比，当在构成单层的直接带隙能量以上进行光激发时，MoSeMoS异质双层的超快太赫兹反射率提高了许多倍。异质双层中产生的自由载流子以在两个单层中各自发现的特征时间演化。令人惊讶的是，当在MoS带隙能量以下激发时，异质双层的超快太赫兹反射率也有同样的增强。提出了一种解释这些观察结果的机制。
