Jiang Sai, Wang Qijing, Qian Jun, Guo Jianhang, Duan Yiwei, Wang Hengyuan, Shi Yi, Li Yun
National Laboratory of Solid-State Microstructures, School of Electronic Science and Engineering, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, Jiangsu 210093, P. R. China.
ACS Appl Mater Interfaces. 2020 Jun 10;12(23):26267-26275. doi: 10.1021/acsami.0c04873. Epub 2020 May 27.
Despite the great efforts to unveil the charge carrier behavior at the semiconductor/dielectric interface of organic field-effect transistors, an examination of the interfacial carrier distribution and the correlation with the charge transport in molecular crystalline semiconductors remains fundamental for understanding the nature of the microscopic carrier motion. Hence, an effective approach to accurately tune the carrier distribution with molecular-layer precision is essential. Here, we find that the carrier accumulation is strictly modulated in highly ordered, few-layer molecular crystalline semiconducting films by tuning the polaronic coupling between the charge carriers and dielectric. The admittance method reveals that the carriers distribute only within a monolayer with stronger localization on a high-κ dielectric and extend to a second layer with better delocalization on a low-κ dielectric. Furthermore, a unique dimensional transition in the charge transport at the dielectric interface is evidenced under a transistor architecture by temperature-dependent measurements. The presented microscopic nature of charge carriers with layer-defined precision in molecular crystalline films should provide an unprecedented opportunity in organic electronics in terms of interface engineering, quantum transport, and device physics.
尽管人们为揭示有机场效应晶体管半导体/电介质界面处的载流子行为付出了巨大努力，但研究分子晶体半导体中的界面载流子分布及其与电荷传输的相关性，对于理解微观载流子运动的本质仍然至关重要。因此，一种能够以分子层精度精确调节载流子分布的有效方法至关重要。在此，我们发现，通过调节电荷载流子与电介质之间的极化子耦合，在高度有序的少层分子晶体半导体薄膜中，载流子积累受到严格调制。导纳方法表明，载流子仅分布在单层内，在高κ电介质上具有更强的局域化，而在低κ电介质上则扩展到第二层且具有更好的离域化。此外，通过温度相关测量在晶体管结构下证明了电介质界面处电荷传输中独特的维度转变。在分子晶体薄膜中呈现的具有层定义精度的电荷载流子微观本质，在界面工程、量子传输和器件物理方面应为有机电子学提供前所未有的机遇。
