A direct comparison of CVD-grown and exfoliated MoS2 using optical spectroscopy
A direct comparison of CVD-grown and exfoliated MoS2 using optical spectroscopy
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DOI：
10.1088/0268-1242/29/6/064008
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发表时间：
2014-06-01
影响因子：
1.9
通讯作者：
Korn, T.
中科院分区：
文献类型：
--
作者：
Plechinger, G.;Mann, J.;Korn, T.
二硫化钼是一种非常有趣的材料，它表现出从体晶体中的间接带隙到单层的直接带隙的交叉。在这里，我们直接比较了化学气相沉积法（CVD）生长的大面积MoS2薄膜和机械剥离法从矿物块晶体中制备的MoS2薄片。拉曼光谱测量显示了在cvd生长和剥离的二硫化钼中面内和面外声子模式位置的差异。光致发光（PL）映射揭示了cvd生长的薄膜在室温下发射强PL的大区域，低温PL扫描显示a激子发射的光谱位移作为位置的函数。在近共振激励条件下的偏振分辨PL测量表明，PL具有强圆偏振，对应于谷偏振。
MoS2 is a highly interesting material, which exhibits a crossover from an indirect band gap in the bulk crystal to a direct gap for single layers. Here, we perform a direct comparison between large-area MoS2 films grown by chemical vapor deposition (CVD) and MoS2 flakes prepared by mechanical exfoliation from mineral bulk crystal. Raman spectroscopy measurements show differences between the in-plane and out-of-plane phonon mode positions in CVD-grown and exfoliated MoS2. Photoluminescence (PL) mapping reveals large regions in the CVD-grown films that emit strong PL at room-temperature, and low-temperature PL scans demonstrate a large spectral shift of the A exciton emission as a function of position. Polarization-resolved PL measurements under near-resonant excitation conditions show a strong circular polarization of the PL, corresponding to a valley polarization.