[论文解读] Molecular Electronics by Chemical Modification of Semiconductor Surfaces

Ayelet Vilan, David Cahen|arXiv (Cornell University)|Dec 11, 2016

Molecular Junctions and Nanostructures参考文献 211被引用 109

一句话总结

对分子单层在金属/半导体界面处的化学修饰如何调控能级对齐、钝化态、诱导偶极、以及驱动电荷重排以影响混合设备中的传输的综述。

ABSTRACT

Inserting molecular monolayers within metal / semiconductor interfaces provides one of the most powerful expressions of how minute chemical modifications can affect electronic devices. This topic also has direct importance for technology as it can help improve the efficiency of a variety of electronic devices such as solar cells, LEDs, sensors and possible future bioelectronic devices, which are based mostly on non-classical semiconducting materials (section 1). The review covers the main aspects of using chemistry to - control alignment of energy levels at interfaces (section 2): - passivate interface states (section 3), - insert molecular dipoles at interfaces (section 4), - induce charge rearrangement at and around interfaces (section 5). After setting the stage, we consider the unique current-voltage characteristics that result from transport across metal / molecular monolayer / semiconductor interfaces. Here we focus on the interplay between the monolayer as tunneling barrier on the one hand, and the electrostatic barrier within the semiconductor, due to its space-charge region (section 6), on the other hand, as well as how different monolayer chemistries control each of the these barriers. Section 7 provides practical tools to experimentally identify these two barriers, and distinguish between them, after which section 8 concludes the story with a summary and a view to the future. While this review is concerned with hybrid semiconductor / molecular effects (see Refs. 1,2 for earlier reviews on this topic), issues related to formation of monolayers and contacts, as well as charge transport that is solely dominated by molecules, have been reviewed elsewhere[3-6], including by us recently[7].

研究动机与目标

• 解释化学如何控制金属/半导体界面的能级对齐。
• 讨论通过钝化界面态来提升器件性能。
• 描述插入界面的分子偶极如何影响静电学与传输。
• 分析由分子层引发的界面及其周围的电荷重排。
• 总结用于识别并区分界面势垒的实际实验方法。

提出的方法

• 综述分子单层作为隧穿势垒的作用及其与半导体空间电荷区的相互作用。
• 讨论单层化学修饰如何调节界面能级对齐和偶极矩。
• 概述在 M-MOS（金属–分子–半导体）结构中分离静电势垒和隧穿势垒的实验技术。
• 综合先前关于纳米结构界面以及混合半导体/分子效应的工作。

实验结果

研究问题

• RQ1 分子单层如何修改金属/半导体界面的能级对齐？
• RQ2 哪些机制支配通过分子修饰对界面态的钝化？
• RQ3 分子偶极和电荷重排如何影响混合界面的传输？
• RQ4 如何在这些体系中从实验上区分隧穿势垒与半导体空间电荷势垒？

主要发现

• 分子单层可通过偶极矩来改变界面能级。
• 化学修饰可钝化界面态以改善器件行为。
• 单层作为隧穿势垒，其效应与半导体空间电荷区域相竞争。
• 单层化学在界面及其周围控制静电势垒和电荷分布。
• 存在用于实验识别并区分这两大势垒的实用工具。
• 综述强调分子效应与半导体效应在金属/分子/半导体界面传输中的相互作用。