An in‐depth analysis of physics in 2D materials like transition metal dichalcogenides requires the measurement of many material properties as a function of Fermi level position within the electronic band structure. This is normally done by changing the charge carrier density of the 2D material via the gate electric field effect. Herein, a comparison of gate‐dependent measurements, which are acquired under different measurement conditions, is shown to encounter significant problems due to the temporal evolution of the charging of trap states inside the dielectric layer or at its interfaces. The impact of, e.g., the gate sweep direction and the sweep rate on the overall gate dependence gets especially prominent in optical measurements due to photoexcitation of donor and acceptor states. Under such conditions, the same nominal gate voltage may lead to different gate‐induced charge carrier densities and, hence, Fermi level positions. It is demonstrated that a current flow from or even through the dielectric layer via leakage currents can significantly diminish the gate tunability in optical measurements of 2D materials.

中文翻译：

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光敏栅屏蔽和漏电流如何动态改变2D材料中的费米能级

深入分析2D材料（例如过渡金属二卤化物）中的物理学，需要对许多材料性能进行测量，以作为电子能带结构内费米能级位置的函数。通常，这是通过栅极电场效应改变2D材料的电荷载流子密度来完成的。在此，由于在电介质层内部或其界面处的陷阱态电荷随时间演变，因此在不同测量条件下获得的与门相关的测量结果的比较显示遇到了重大问题。由于施主和受主态的光激发，例如栅极扫描方向和扫描速率对整体栅极依赖性的影响在光学测量中尤为突出。在这种情况下 相同的标称栅极电压可能会导致不同的栅极感应电荷载流子密度，从而产生费米能级位置。已经证明，在2D材料的光学测量中，通过泄漏电流从电介质层流出或什至流经电介质层的电流会显着降低栅极可调性。