Coupling of tribovoltaic effect and tribo-electrostatic effect at dynamic semiconductor heterojunction interfaces

Abstract

Tribovoltaic effect at the dynamic semiconductor interface is of great fundamental and practical importance for developing a variety of functional devices; yet, it can be coupled with a series of different physical effects, such as the contact-electrification induced electrostatic effect and mechanical wearing effect, and the coupling mechanisms are still remained to be elucidated. Herein, we investigated the coupling between tribovoltaic and tribo-electrostatic effects at the dynamic heterojunctions of two wide-bandgap semiconductors: zinc oxide (ZnO) and gallium nitride (GaN). It is found that, in the contact-separation mode, the direct-current outputs from tribovoltaic effect can be clearly distinguished from the alternating-current outputs from tribo-electrostatic effect. Then, humidity, external load resistance and pressure force are found to reveal the coupling characteristics of these two effects, that tribovoltaic outputs are less affected by humidity, show smaller matched impedance and are more sensitive to high pressure force, diverging from the tribo-electrostatic outputs. Lastly, we demonstrate that the mechanical wearing effect can be inhibited in contact-separation mode, achieving long-term stability over 50,000 cycles. Therefore, this work provides insights to the mechanism of tribovoltaic effects and practical guidance for high-performances tribovoltaic devices.