Polarity-Dependent Piezotronic Effect and Controllable Transport Modulation of ZnO with Multifield Coupled Interface Engineering

Interface engineering has emerged as a powerful approach for nanodevices performance manipulation. Nevertheless, most of previous work mainly focuses on interface modulation with single physical field, such as strain or light, little work has been reported on their coupling effect. Here, using patterned and polarity-controlled ZnO nanorods, the authors present a systematic multifield coupling investigation with photo-atomic force microscope, where an optical system is introduced and 355 nm UV laser with tunable power can precisely illuminate sample under conductive tip. Surface polarity-dependent tailoring of interfacial barrier is demonstrated, which verifies the dominant role of polar piezotronic effect. Furthermore, coupled modulation of piezopolarization and photoexcitation on local transport property is studied. Fine tuning of transport characteristics is achieved through subtly adjusting applied force and illumination power. The results offer an applicable method to realize tunable interface property with coupled external stimuli and can be potentially expanded to other noncentral symmetric structure nanowire or novel 2D layered piezoelectric materials.