Atomic-layer triangular WSe2 sheets: synthesis and layer-dependent photoluminescence property
Atomic-layer triangular WSe2 sheets: synthesis and layer-dependent photoluminescence property
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DOI：
10.1088/0957-4484/24/46/465705
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发表时间：
2013-10
期刊：
影响因子：
3.5
通讯作者：
Kai Xu;Zhenxing Wang;Xiao-qing Du;M. Safdar;Chao Jiang;Jun He
中科院分区：
文献类型：
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作者：
Kai Xu;Zhenxing Wang;Xiao-qing Du;M. Safdar;Chao Jiang;Jun He
二维材料奇特的能带结构和独特的物理性质在自旋电子学、电子学、光子学、光电子学等领域显示出巨大的基础研究和技术应用潜力。面对有效合成WSe_2二维薄片的挑战，我们首次提出了一种直接的无催化剂气-固(VS)生长方法，在蓝宝石衬底上合成了高产量、规则形状和高质量光学性能的超薄、均匀的单层WSe_2薄片。在40K的低温下，通过详细的与层数相关的光致发光测量，我们发现WSe2价带K点的自旋-轨道分裂，其固定能差为0.36 eV，与层数无关，并在厚度减小到单分子层时发生了间接带隙到直接带隙的转变。这些结果与机械剥离WSe2薄膜的结果相当，进一步证明了我们通过VS生长方法制备的WSe2纳米薄膜具有高光学和高晶体质量。我们的努力可能会在未来基于山谷的电子、光电子和光电子领域开辟新的令人兴奋的机会。
The exotic band structures and distinctive physical properties of two-dimensional materials have exhibited great potential for fundamental research and technical applications in spintronics, electronics, photonics, optoelectronics, and so forth. Facing the challenge of effective synthesis of WSe2 two-dimensional sheets, for the first time we demonstrate a straightforward catalyst-free vapor–solid (VS) growth method to synthesize ultrathin, even monolayer, WSe2 sheets with high yield, regular shapes and high quality optical properties on sapphire substrates. By detailed layer-number-dependent photoluminescence measurements at a low temperature of 40 K, we find the spin–orbit splitting at the K point of the WSe2 valence band with a fixed energy difference of 0.36 eV independent of layer number and the transition of indirect-to-direct gap when the thickness decreases to monolayer. These results, comparable to those of mechanically peeled WSe2 sheets, further prove the high optical and crystal quality of our WSe2 nanosheets via the VS growth approach. Our efforts may open up new exciting opportunities in future valley-based electronics, optoelectronics and photonics.