Current degradation mechanism of tip contact metal-silicon Schottky nanogenerator

• Published in: Nano energy 2022-04, Vol.94, p.106888, Article 106888
• Main Authors: Deng, Shuo, Xu, Ran, Seh, Weibin, Sun, Jiayi, Cai, Weifan, Zou, Jianping, Zhang, Qing
• Format: Article
• Language: English
• Subjects: Atomic force microscope; Schottky nanogenerator; Tribo-tunneling effect; Tribo-voltaic effect
• ISSN: 2211-2855
• DOI: 10.1016/j.nanoen.2021.106888

It has been recently found that a direct current (DC) can be generated through sliding a metal tip (or electrode) against a doped semiconductor if the two materials are of distinct work functions. However, it is also well observed that the DC current generation is degraded if the sliding is repeatedly performed over the same area. Thus, to maintain a stable DC current generation is challenging. In this paper, we present that an ultrathin silicon oxide layer is induced during sliding a platinum coated atomic force microscope tip on a clean doped silicon substrate. With increasing number of sliding over the same area, electron transfer across the tip contacted surface changes from a tribo-voltaic process to a tribo-tunneling process. Moreover, it is also observed that current degradation can be mitigated if the clean silicon substrate is annealed nitrogen. This work not only provides new understanding of electron transfer process in the dynamic Schottky junctions, but also suggests a route for further optimization of the junctions for stable current generation. [Display omitted] •Silicon oxide layer at contact interface of metal-silicon Schottky nanogenerator is demonstrated.•Silicon oxide layer induce electron transfer changed from the tribo-voltaic process to the tribo-tunneling process.•Interaction between the build-in electric field and adsorbed water molecules formed the silicon oxide layer.•The current degradation process can be mitigated after the silicon substrate is annealed and slid in nitrogen environment.