Ultra-low power threshold for laser induced changes in optical properties of 2D molybdenum dichalcogenides
Ultra-low power threshold for laser induced changes in optical properties of 2D molybdenum dichalcogenides
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DOI：
10.1088/2053-1583/3/4/045008
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发表时间：
2016-12-01
期刊：
影响因子：
5.5
通讯作者：
Urbaszek, Bernhard
中科院分区：
文献类型：
--
作者：
Cadiz, Fabian;Robert, Cedric;Urbaszek, Bernhard
传统半导体的光学响应取决于实验中使用的激光激发功率。对于二维（2D）半导体，激光激发效应预计将有很大的不同，由于其最终的薄，高表面体积比，和激光膜相互作用的影响，增加了复杂性。在真空中，二维材料的光学性质在激光激发下发生不可逆的变化。最令人惊讶的是，即使在低稳态激发下也会发生这些效应，这通常被认为是非侵入性的。在低温光致发光（PL），我们表明单层（ML）MoSe 2样品生长通过不同的技术，激光处理显着增加的trion（即带电激子）的贡献相比，中性激子发射的发射。剥离到不同基板上的样品之间的比较表明，激光诱导掺杂是更有效的ML MoSe 2 SiO2/Si相比，h-BN和金。对于ML二硫化钼，我们表明，暴露于μ W μ m（-2）范围内的平均功率的激光辐射不只是增加的trion激子PL发射比，但可能会导致不可逆的中性激子PL发射的消失和PL主峰的位移到较低的能量。
The optical response of traditional semiconductors depends on the laser excitation power used in experiments. For two-dimensional (2D) semiconductors, laser excitation effects are anticipated to be vastly different due to complexity added by their ultimate thinness, high surface to volume ratio, and laser-membrane interaction effects. Weshow in this article that under laser excitation the optical properties of 2D materials undergo irreversible changes in vacuum. Most surprisingly these effects take place even at low steady state excitation, which is commonly thought to be non-intrusive. In low temperature photoluminescence (PL) we show for monolayer (ML) MoSe2 samples grown by different techniques that laser treatment increases significantly the trion (i.e. charged exciton) contribution to the emission compared to the neutral exciton emission. Comparison between samples exfoliated onto different substrates shows that laser induced doping is more efficient for ML MoSe2 on SiO2/Si compared to h-BN and gold. For ML MoS2 we show that exposure to laser radiation with an average power in the mu W mu m(-2) range does not just increase the trion-to-exciton PL emission ratio, but may result in the irreversible disappearance of the neutral exciton PL emission and a shift of the main PL peak to lower energy.