Suppression of Defects and Deep Levels Using Isoelectronic Tungsten Substitution in Monolayer MoSe2
Suppression of Defects and Deep Levels Using Isoelectronic Tungsten Substitution in Monolayer MoSe2
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DOI：
10.1002/adfm.201603850
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发表时间：
2017-05-18
影响因子：
19
通讯作者：
Xiao, Kai
中科院分区：
文献类型：
--
作者：
Li, Xufan;Puretzky, Alexander A.;Xiao, Kai
二维（2D）过渡金属二硫属化物（TMD）的化学气相沉积（CVD）过程中形成的缺陷目前限制了它们的质量和光电性能。有效的合成和处理策略，以抑制缺陷和提高2D TMD的质量，迫切需要使下一代光电器件。在这项工作中，等电子掺杂作为一种新的策略，以形成稳定的合金，抑制缺陷，并提高在CVD生长的TMD单分子膜的光致发光（PL）。在CVD生长的Mo 1-xWxSe 2（0 < x < 0.18）单层中，W原子对Mo原子的等电子取代显示出与原始MoSe 2单层中发现的那些相比，有效地将Se空位浓度抑制50%，导致缺陷介导的非辐射复合的减少，接近10倍更强的PL，并且载流子寿命增加3倍。理论预测表明，等电子W合金化形成Mo 1-xWxSe 2单层提高了MoSe 2中深能级缺陷的能量，使更快的淬火，这是由低温（4-125 K）PL从缺陷相关的局域态证实。因此，等电子取代似乎是一种有前途的合成方法，以控制2D TMD的异质性，以实现高性能光电和电子器件的可规模化生产。
Defects formed during chemical vapor deposition (CVD) of two-dimensional (2D) transition metal dichalcogenides (TMDs) currently limit their quality and optoelectronic properties. Effective synthesis and processing strategies to suppress defects and enhance the quality of 2D TMDs are urgently needed to enable next generation optoelectronic devices. In this work, isoelectronic doping is presented as a new strategy to form stable alloys and suppress defects and enhance photoluminescence (PL) in CVD-grown TMD monolayers. The isoelectronic substitution of W atoms for Mo atoms in CVD-grown monolayers of Mo1-xWxSe2 (0 < x < 0.18) is shown to effectively suppress Se vacancy concentration by 50% compared to those found in pristine MoSe2 monolayers, resulting in a decrease in defect-mediated nonradiative recombination, approximate to 10 times more intense PL, and an increase in the carrier lifetime by a factor of 3. Theoretical predictions reveal that isoelectronic W alloying to form Mo1-xWxSe2 monolayers raises the energy of deep level defects in MoSe2 to enable faster quenching, which is confirmed by low temperature (4-125 K) PL from defect-related localized states. Isoelectronic substitution therefore appears to be a promising synthetic method to control the heterogeneity of 2D TMDs to realize the scalable production of high performance optoelectronic and electronic devices.