Electrochemically Gated Single Molecule FETs

根据摩尔定律，可以放置在硅片上的元件数量大约每两年翻一番，设备的处理和数据存储能力相应增加，元件的单位成本降低，这一观察结果推动了40年的技术成就和新材料科学。具有45纳米特征尺寸的设备现在正在生产中，具有22纳米特征尺寸的接近市场的芯片正在披露中。然而，为了实现这些非凡的器件尺寸，自上而下的比例正在让位于更复杂、更具光刻挑战性的3-D设计，传统材料被取代。尽管“更多摩尔”仍然是半导体行业的重要推动力，但“比摩尔更多”的概念作为一种设计策略正在发展壮大。“摩尔以上”的概念是，通过添加本身不一定符合摩尔定律的功能，将附加值打包到设备中。将更小、更快的设备技术与创新的全系统封装相结合，现在被视为提高设备性能的最可行途径，因为遵循传统的自上而下扩展越来越困难。无论有没有超过摩尔增长，如果电子设备开发的步伐要继续沿着摩尔定律预测，从长远来看，将需要进一步缩小特征尺寸。这一命题产生了两个后果。首先，从中长期来看，特征尺寸将接近分子尺寸。第二个更实际、更直接的后果是，新材料现在必须集成到硅基设备中。在现在的45纳米芯片中，当晶体管处于关断状态时，二氧化硅栅会非常薄，以至于会泄漏太多的电流。早在确切的材料解决方案构思出来之前，这个问题就已经被认识到了，解决方案(高介电介质替代绝缘体)也很明显。尽管沉积HfO2存在技术挑战，但HfO2现在仍被用作晶体管栅绝缘体。HfO2是一种高耐火和昂贵的材料。因此，虽然“分子电子学”通常被认为很难实现，但“传统”硅技术的持续发展也面临着深刻而困难的挑战，这是工业所适应的。术语“分子电子学”通常用于指设计为涉及两个触点(可能是金属或半导体)之间的单个分子、一小束分子或单层分子的结构，因此触点之间的关键尺寸处于纳米尺寸范围内。分子水平上的电路元件可以利用分子的小尺寸及其在结构和性质上的巨大潜在变化，通过使用合成化学工具来控制，以增加器件密度，并将新功能融入现有或新的微电子体系结构中。这一研究阶段的主要目标是：(A)确定分子材料及其接触的类别，这些材料显示出分子电子学的良好属性；(B)确定和了解可利用其电学性质的机制；(C)进一步开发确定的计量技术，以可靠地确定分子器件的电学行为。为了传达未来的实际意义，我们的重点将放在室温操作和凝聚态界面上。

Moore's Law, the observation that the number of components that can be placed on a silicon chip approximately doubles every two years, with commensurate increases in the processing and data storage capacities of devices, and decreases in the unit cost of components, has driven technological achievement and new materials science for 40 years. Devices featuring <45 nm feature sizes are now in production, and close-to-market chips with 22 nm feature sizes are being disclosed. However, to achieve these remarkable device sizes, top-down scaling is giving way to more complex and lithographically challenging 3-D designs, and conventional materials superseded. Although 'More Moore' remains an important driver for the semiconductor industry, the concept of 'More than Moore', in which added value is packaged into devices by adding functionalities that themselves do not necessarily scale in line with Moore's Law is growing as a design strategy. The integration of smaller and faster device technology with innovative total systems packaging is now seen as the most feasible route to improve device performance, recognising the increasing difficulties in following traditional top-down scaling. With or without More than Moore augmentation, if pace of electronic device development is to continue along a Moore's Law projection in the longer-term further reductions in feature size will be required. Two consequences flow from this proposition. The first is that, in the medium-long term, feature sizes will approach molecular dimensions. The second, more practical and more immediate consequence, is that new materials must now be integrated into silicon-based devices. In the present generation 45 nm chips , a SiO2 gate would be so thin as to leak too much current when the transistor is in the 'off' state. This problem was recognised, and the solution (a high-dielectric alternative insulator) apparent, long before the exact materials solution was conceived. HfO2 is now used as the transistor gate insulator despite the technical challenges inherent in depositing HfO2, a highly refractory and expensive material. Thus, while 'molecular electronics' is commonly perceived to be very difficult to implement, the continued development of 'traditional' silicon technology also faces profound and difficult challenges, which industry adapts to meet.The term 'molecular electronics' is generally applied to structures designed to involve a single molecule, a small bundle of molecules, or a single layer of molecules, oriented between two contacts (which may be metals or semiconductors), with the critical dimension between the contacts therefore lying in the nanometer size range. Circuit components at the molecular level could exploit the small size of molecules and their enormous potential variation in structure and properties, controlled using the tools of synthetic chemistry, to increase device density and to incorporate new functionality into existing or new microelectronic architectures. Primary objectives in this research phase are (a) to identify classes of molecular materials, and their contacts, which display promising attributes for molecular electronics, (b) to identify and understand mechanisms by which the electrical properties can be exploited, (c) to further develop defined metrological techniques for reliably determining the electrical behaviour of molecular devices. To convey future practical relevance our focus will be on room temperature operation and condensed matter interfaces.