Intrinsic and Extrinsic Defect-Related Excitons in TMDCs,Nano Letters

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Intrinsic and Extrinsic Defect-Related Excitons in TMDCs
Nano Letters ( IF 9.6 ) Pub Date : 2020-03-19 , DOI: 10.1021/acs.nanolett.9b05323
Kyrylo Greben ₁ , Sonakshi Arora ₁ , Moshe G. Harats ₁ , Kirill I. Bolotin ₁

Affiliation

We investigate the excitonic peak associated with defects and disorder in low-temperature photoluminescence of monolayer transition metal dichalcogenides (TMDCs). To uncover the intrinsic origin of defect-related (D) excitons, we study their dependence on gate voltage, excitation power, and temperature in a prototypical TMDC monolayer MoS₂. Our results suggest that D excitons are neutral excitons bound to ionized donor levels, likely related to sulfur vacancies, with a density of 7 × 10¹¹ cm^–2. To study the extrinsic contribution to D excitons, we controllably deposit oxygen molecules in situ onto the surface of MoS₂ kept at cryogenic temperature. We find that, in addition to trivial p-doping of 3 × 10¹² cm^–2, oxygen affects the D excitons, likely by functionalizing the defect sites. Combined, our results uncover the origin of D excitons, suggest an approach to track the functionalization of TMDCs, to benchmark device quality, and pave the way toward exciton engineering in hybrid organic–inorganic TMDC devices.

中文翻译：

TMDC中内在和外在缺陷相关的激子

我们调查与缺陷和无序相关的在单层过渡金属二卤化金属（TMDCs）的低温光致发光中的激子峰。为了揭示与缺陷相关的（D）激子的内在起源，我们研究了原型DCTM单层MoS _2中它们对栅极电压，激励功率和温度的依赖性。我们的结果表明，D激子是中性激子，与离子化的供体水平结合，可能与硫的空位有关，密度为7×10 ¹¹ cm ^–2。为了研究外源性对D激子的贡献，我们可控地将氧分子原位沉积在保持低温的MoS ₂表面上。我们发现，除了3×10的微不足道的p掺杂之外，¹² cm ^–2，氧可能通过使缺陷部位功能化来影响D激子。综合起来，我们的结果揭示了D激子的起源，提出了一种跟踪TMDC功能的方法，以基准测试设备质量，并为有机-无机TMDC混合设备中的激子工程学铺平了道路。

更新日期：2020-04-24

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