Gallagher Patrick, Lee Menyoung, Petach Trevor A, Stanwyck Sam W, Williams James R, Watanabe Kenji, Taniguchi Takashi, Goldhaber-Gordon David
Department of Physics, Stanford University, Stanford, California 94305, USA.
Department of Applied Physics, Stanford University, Stanford, California 94305, USA.
Nat Commun. 2015 Mar 12;6:6437. doi: 10.1038/ncomms7437.
Electrolyte gating is a powerful technique for accumulating large carrier densities at a surface. Yet this approach suffers from significant sources of disorder: electrochemical reactions can damage or alter the sample, and the ions of the electrolyte and various dissolved contaminants sit Angstroms from the electron system. Accordingly, electrolyte gating is well suited to studies of superconductivity and other phenomena robust to disorder, but of limited use when reactions or disorder must be avoided. Here we demonstrate that these limitations can be overcome by protecting the sample with a chemically inert, atomically smooth sheet of hexagonal boron nitride. We illustrate our technique with electrolyte-gated strontium titanate, whose mobility when protected with boron nitride improves more than 10-fold while achieving carrier densities nearing 10(14) cm(-2). Our technique is portable to other materials, and should enable future studies where high carrier density modulation is required but electrochemical reactions and surface disorder must be minimized.
电解质门控是一种在表面积累大量载流子密度的强大技术。然而，这种方法存在显著的无序来源：电化学反应会损坏或改变样品，并且电解质离子和各种溶解的污染物与电子系统相距埃级距离。因此，电解质门控非常适合用于研究对无序具有鲁棒性的超导性和其他现象，但在必须避免反应或无序的情况下用途有限。在此，我们证明通过用化学惰性、原子级光滑的六方氮化硼薄片保护样品，可以克服这些限制。我们用电解质门控的钛酸锶来说明我们的技术，在用氮化硼保护时，其迁移率提高了10倍以上，同时实现了接近10(14) cm(-2)的载流子密度。我们的技术可移植到其他材料上，并且应该能够实现未来需要高载流子密度调制但必须尽量减少电化学反应和表面无序的研究。
