Electrochemically Gated Single Molecule FETs

摩尔定律指出，随着设备处理和数据存储能力的相应提高，硅芯片上可容纳的组件数量每两年翻一番，而组件的单位成本则相应降低，这一定律推动了40年来的技术成就和新材料科学。小于45纳米特征尺寸的器件目前正在生产中，而接近市场的22纳米特征尺寸芯片正在公开。然而，为了实现这些显着的器件尺寸，自上而下的缩放正在让位于更复杂和具有光刻挑战性的3-D设计，传统材料被取代。虽然“More Moore”仍然是半导体行业的重要驱动力，但“More than Moore”的概念正在成为一种设计策略，即通过添加自身不一定符合摩尔定律的功能来封装设备的附加价值。将更小、更快的设备技术与创新的整体系统封装相结合，现在被视为提高设备性能的最可行途径，认识到遵循传统的自上而下的扩展越来越困难。无论是否有摩尔增强，如果电子设备的发展速度继续沿着摩尔定律的预测，在更长的时间内，将需要进一步缩小特征尺寸。这个命题引出了两个结果。首先，在中长期内，特征尺寸将接近分子尺寸。第二，更实际和更直接的后果是，现在必须将新材料集成到硅基器件中。在目前的45纳米芯片中，SiO2栅极太薄，以至于当晶体管处于“关”状态时漏出太多电流。早在确切的材料解决方案被设想出来之前，这个问题就被认识到了，解决方案（一种高介电性的替代绝缘体）也很明显。HfO2现在被用作晶体管栅极绝缘体，尽管沉积HfO2这种高度难熔且昂贵的材料存在固有的技术挑战。因此，虽然“分子电子学”通常被认为是非常难以实施的，但“传统”硅技术的持续发展也面临着深刻而困难的挑战，这些挑战是行业适应的。术语“分子电子学”通常适用于设计涉及单个分子，一小束分子或单层分子的结构，定向在两个触点之间（可能是金属或半导体），因此触点之间的关键尺寸位于纳米尺寸范围内。在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能上的巨大潜在变化，使用合成化学工具进行控制，以增加设备密度并将新功能纳入现有或新的微电子架构中。本研究阶段的主要目标是(a)确定分子材料的类别及其接触，它们显示出分子电子学的有前途的属性，(b)识别和理解可以利用电学特性的机制，(c)进一步开发定义的计量技术，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top-down scaling is giving way to more complex and lithographically challenging 3-D designs, and conventional materials superseded.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.