Vaz Diogo Castro, Lesne Edouard, Sander Anke, Naganuma Hiroshi, Jacquet Eric, Santamaria Jacobo, Barthélémy Agnès, Bibes Manuel
Unité Mixte de Physique CNRS/Thales, Université Paris-Saclay;
Unité Mixte de Physique CNRS/Thales, Université Paris-Saclay; Max Planck Institut für Mikrostrukturphysik.
J Vis Exp. 2018 Feb 8(132):56951. doi: 10.3791/56951.
The quasi 2D electron system (q2DES) that forms at the interface between LaAlO3 (LAO) and SrTiO3 (STO) has attracted much attention from the oxide electronics community. One of its hallmark features is the existence of a critical LAO thickness of 4 unit-cells (uc) for interfacial conductivity to emerge. Although electrostatic mechanisms have been proposed in the past to describe the existence of this critical thickness, the importance of chemical defects has been recently accentuated. Here, we describe the growth of metal/LAO/STO heterostructures in an ultra-high vacuum (UHV) cluster system combining pulsed laser deposition (to grow the LAO), magnetron sputtering (to grow the metal) and X-ray photoelectron spectroscopy (XPS). We study step by step the formation and evolution of the q2DES and the chemical interactions that occur between the metal and the LAO/STO. Additionally, magnetotransport experiments elucidate on the transport and electronic properties of the q2DES. This systematic work not only demonstrates a way to study the electrostatic and chemical interplay between the q2DES and its environment, but also unlocks the possibility to couple multifunctional capping layers with the rich physics observed in two-dimensional electron systems, allowing the fabrication of new types of devices.
在氧化镧铝（LAO）和钛酸锶（STO）界面形成的准二维电子系统（q2DES）引起了氧化物电子学界的广泛关注。其一个标志性特征是，当界面电导率出现时，存在一个4个晶胞（uc）的临界LAO厚度。尽管过去曾提出静电机制来描述这个临界厚度的存在，但最近化学缺陷的重要性得到了强调。在这里，我们描述了在超高真空（UHV）簇系统中金属/LAO/STO异质结构的生长过程，该系统结合了脉冲激光沉积（用于生长LAO）、磁控溅射（用于生长金属）和X射线光电子能谱（XPS）。我们逐步研究了q2DES的形成和演化，以及金属与LAO/STO之间发生的化学相互作用。此外，磁输运实验阐明了q2DES的输运和电子特性。这项系统性工作不仅展示了一种研究q2DES与其环境之间静电和化学相互作用的方法，还开启了将多功能覆盖层与二维电子系统中观察到的丰富物理现象相结合的可能性，从而能够制造新型器件。
