论文标题
通过确定性的扁平化制备的超平淡单层mose2中增强的激子 - 表面碰撞
Enhanced exciton-exciton collisions in an ultra-flat monolayer MoSe2 prepared through deterministic flattening
论文作者
论文摘要
通过在几层石墨烯盖上限施加力的情况下，从层间空间中挤出气泡和杂质，导致范德华的异质结构，其超纤维结构不含带电杂质引起的随机静电电势。没有石墨烯封顶层，具有AFM尖端的挤压过程会诱导n〜2 x 10^12 cm^-2 Un^-1的施加依赖性电荷，从而导致在低温下Mose2的光致发光光谱中的Trions强度强。我们发现，用“改良的纳米块方法”制备的HBN/Mose2/HBN显示出强烈的激发发射，具有可忽略的TRION峰，而激子峰的残留线宽仅为2.2 MeV，这与同质极限相当。此外，在这个高质量的样本中，我们发现Biexciton的形成甚至在极低的激发能力（PHI〜2.3 x 10^19 cm^-2 s^-1）中，由于激发量增强了碰撞。
Squeezing bubbles and impurities out of interlayer spaces by applying force through a few-layer graphene capping layer leads to van der Waals heterostructures with ultra-flat structure free from random electrostatic potential arising from charged impurities. Without the graphene capping layer, a squeezing process with an AFM tip induces applied-force-dependent charges of n ~ 2 x 10^12 cm^-2 uN^-1, resulting in strong intensity of trions in photoluminescence spectra of MoSe2 at low temperature. We found that a hBN/MoSe2/hBN prepared with the "modified nano-squeezing method" shows a strong excitonic emission with negligible trion peak, and the residual linewidth of the exciton peak is only 2.2 meV, which is comparable to the homogeneous limit. Furthermore, in this high-quality sample, we found that formation of biexciton occurs even at extremely low excitation power (Phi ~ 2.3 x 10^19 cm^-2 s^-1) due to the enhanced collisions between excitons.
