The piezopotential generated in non-centrosymmetric crystals under external mechanical stimuli can be exploited to modulate the contact characteristics at the metal-semiconductor interface. The extent of electric modulation by the piezopotential was found to be moderate. This is mainly because the piezopotential was designed to alter the band bend of the semiconductor layer, which changed the injection barrier by 0.1 eV. We propose an efficient method to utilize the piezopotential for modulating Schottky barrier, i.e. piezotronic graphene barristor. This was done by capacitively coupling the piezoelectric material with a Schottky barrier (SB)-tunable graphene electrode, using an ion gel electrolyte. Through capacitive coupling, the piezopotential could modulate the work function of a graphene electrode by 0.89 eV. This was visualized directly using Kelvin probe force microscopy experiments for the first time. A large change in the work function of graphene allowed effective tuning of the height of the SB formed at the graphene/semiconductor junction. Consequently, a piezoelectric nanogenerator (PENG) could change the current density of the semiconductor layer by more than three orders of magnitude with strain, and yield a high current density larger than 10.5 A cm-2. Multistage modulation of the height of the SB at the junction was also successfully demonstrated by integrating two PENGs with ion gel. This work presents an efficient method for harnessing the piezopotential generated from PENG to actively control the operation of flexible electronics through external mechanical stimuli.
Bibliographical noteFunding Information:
Q. Sun was supported financially by the support of the National Key Research and Development Program of China ( 2016YFA0202703 ), National Natural Science Foundation of China (Grand nos. 51605034 and 51711540300 ), the “Hundred Talents Program” of the Chinese Academy of Science, and the "thousands talents" program for pioneer researcher and his innovation team. This work was also supported financially by a grant from the Center for Advanced Soft Electronics (CASE) under the Global Frontier Research Program ( 2013M3A6A5073177 ), the Basic Science Research Program through a National Research Foundation of Korea grant funded by the Korean Government (MEST) ( 2017R1A4A1015400 ), and the Pioneer Research Center Program (Grant no. 2014M3C1A3053024 ), Korea.
© 2018 Elsevier Ltd
All Science Journal Classification (ASJC) codes
- Renewable Energy, Sustainability and the Environment
- Materials Science(all)
- Electrical and Electronic Engineering