On the Photo‐Carriers Dynamic Regulation by Piezo‐Phototronic Effect in Metal‐Oxide–Semiconductor Tunneling Junction

Abstract

Abstract The piezo‐phototronic effect can modulate the dynamics of photo‐generated carriers by utilizing external‐strain–induced piezoelectric charges (piezo‐charges). Most of the current researches focus on the modulation effect on the optoelectronic properties of p–n junctions. There are only a few studies focusing on the metal‐oxide–semiconductor (MOS) structures. In this work, a PEDOT:PSS/Al2O3/n‐ZnO tri‐layer MOS tunneling junction is fabricated and the piezo‐phototronic effect on its photo‐carriers dynamic and performances is systematically investigated. The photoresponsivity to 365 nm laser illumination is reduced because of the negative piezo‐charges generated at the Al2O3/n‐ZnO interface. Meanwhile but unexpectedly, the similar phenomenon utilizing the positive piezo‐charges at the Al2O3/n‐ZnO interface is observed. The in‐depth working mechanisms are carefully investigated by analyzing the effect of piezo‐charges on the energy band diagram. Strain induced piezo‐charges could feasibly adjust the intermediate oxide layer's barrier height and width so that the tunneling effect can be efficiently modulated by the piezo‐phototronic effect, leading to the effective control over the MOS tunneling junction's photo‐carriers dynamic and corresponding photoresponses. This work provides an in‐depth understanding for the piezo‐phototronic effect on the MOS tunneling junction and provides guidance for the subsequent researches on the coupling of piezo‐phototronic effect and tunneling effect.

Keywords

• Fowler–Nordheim tunneling
• metal‐oxide–semiconductor
• piezo‐phototronic effect
• ZnO