Atomic Layer Interface Engineering for Nanoelectronics (ALIEN): Contacts

纳米电子学原子层接口工程 (ALIEN)：联系方式

• 批准号: EP/J010944/1
• 负责人: Anthony O'Neill
• 金额: $ 75.57万
• 依托单位: Newcastle University
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2012
• 资助国家: 英国
• 起止时间: 2012 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=EP%2FJ010944%2F1
• 关键词: Atomic; Layer; Interface; Engineering; Nanoelectronics

This research considers the intriguing prospect of using insulators to improve electrical conductivity. The revolution in electronics over the last 50 years is due in large part to semiconductors, including silicon for microchips, III-V semiconductors for optical components such as lasers or LEDs and organic semiconductors for large area displays. Electrical contact from a metal to these semiconductors is fundamental. Conventional theory, developed by Schottky and Mott in the 1930's and still taught today, says that the potential energy barrier that electrons encounter at the junction between a metal and a semiconductor is simply the difference in energy needed to take electrons from each material (the workfunction difference). Thus by a suitable choice of semiconductor and metal, the energy to remove electrons from either will be the same and there should be no barrier to current between them. But experience shows this is generally not the case, particularly for semiconductors of commercial interest. In fact, the potential energy barrier (the Schottky barrier) tends to be about the same for all metal contacts to any given semiconductor. The effect is called Fermi level pinning and arises because electrons from the metal spill into the semiconductor at the junction. The barrier gives rise to an electrical resistance, which may be different depending on the direction of current (a Schottky diode). The resistance can belowered by making the contact surface area large and/or by increasing doping in the semiconductor so that the potential energy barrier becomes thin enough that electrons can easily tunnel through. But this is not always possible or sufficient. A novel approach to improving the electrical contact is to add a thin insulator in between the metal and the semiconductor. The effect is to prevent electrons spilling from the metal into the semiconductor and so prevent Fermi level pinning. The correct choice of metal and semiconductor will allow a reduction in potential energy barrier height, as Schottky-Mott theory suggests. A complication is that the insulator itself may block current and so needs to be thin (~ nm scale). This research will deposit nm scale insulating layers between semiconductors and metals to improve conduction across the contact. A range of experimental techniques will be used to measure the change in electrical properties brought about by the thin insulator films and the film thickness will be optimised for a range of important semiconductors. Modelling of the atomic structure of the metal, insulator and semiconductor will help to unravel to competing factors that are at play in improving current flow. The research will also address integrating this type of contact into a manufactured device, 3D structures and to test its applicability to organic semiconductors.

这项研究考虑了利用绝缘体提高导电性的耐人寻味的前景。过去50年的电子革命在很大程度上归功于半导体，包括用于微芯片的硅，用于激光或LED等光学元件的III-V半导体，以及用于大面积显示器的有机半导体。金属与这些半导体之间的电接触是最基本的。传统理论由肖特基和莫特在20世纪30年代的S提出，至今仍在教授。该理论认为，电子在金属和半导体交界处遇到的势垒只是从每种材料中获取电子所需的能量之差(功函数差)。因此，通过选择合适的半导体和金属，从两者中移除电子的能量将是相同的，并且它们之间应该没有电流障碍。但经验表明，情况通常并非如此，尤其是对具有商业利益的半导体。事实上，对于任何给定半导体的所有金属接触，势能垒(肖特基势垒)往往是相同的。这种效应被称为费米能级钉扎，是因为金属中的电子在结合处溢出到半导体中而产生的。势垒产生电阻，根据电流方向(肖特基二极管)的不同，电阻可能不同。可以通过增大接触表面积和/或增加半导体中的掺杂来降低电阻，从而使势垒变得足够薄，以便电子可以很容易地穿透。但这并不总是可能或充分的。一种改善电接触的新方法是在金属和半导体之间增加一个薄绝缘体。其效果是防止电子从金属溢出到半导体中，从而防止费米能级钉扎。正如肖特基-莫特理论所表明的那样，正确选择金属和半导体将允许降低势垒高度。一个复杂的问题是，绝缘体本身可能会阻挡电流，因此需要很薄(~nm尺度)。这项研究将在半导体和金属之间沉积纳米级绝缘层，以改善接触的导电性。将使用一系列实验技术来测量薄绝缘膜带来的电学性能变化，并对一系列重要半导体的膜厚度进行优化。对金属、绝缘体和半导体的原子结构进行建模，将有助于揭示在改善电流流动方面发挥作用的竞争因素。这项研究还将致力于将这种类型的接触集成到制造的设备--3D结构中，并测试其对有机半导体的适用性。

项目成果

Improving metal/semiconductor conductivity using AlO x interlayers on n-type and p-type Si

• DOI: 10.1063/1.4892003
• 发表时间: 2014-08
• 期刊: Applied Physics Letters
• 影响因子: 4
• 作者: P. King;E. Arac;S. Ganti;Kelvin S. K. Kwa;N. Ponon;A. O'Neill

Voltage Controlled Hot Carrier Injection Enables Ohmic Contacts Using Au Island Metal Films on Ge.

• DOI: 10.1021/acsami.7b06595
• 发表时间: 2017-08
• 期刊: ACS applied materials & interfaces
• 影响因子: 9.5
• 作者: S. Ganti;P. King;E. Arac;K. Dawson;Mikko J. Heikkilä;J. H. Quilter;B. Murdoch;P. Cumpson;A. O'Neill