Piezotronics and piezo-phototronics based on a-axis nano/microwires: fundamentals and applications

One-dimensional semiconductors with wurtzite structure, such as GaN, ZnO and CdS nano/microwires, exhibit superior semiconductor, piezoelectric and mechanical properties, making them excellent candidates for novel electronic, opto-electronic devices and integrated systems. More importantly, the coupling between piezoelectric polarization and semiconductor properties ( including electric transport and photoexcitation) gives rise to unique and unprecedented physical characteristics and has led to emerging fields of piezotronics and piezo-phototronics. On the basis of the extensive studies in c-axis semiconductor nano/microwires, piezotronics and piezo-phototronics based on a-axis nano/microwires have further been explored and demonstrated recently. We review both the fundamental progresses and developed applications of piezotronics and piezo-phototronics based on a-axis nano/microwires, which further improve the theoretical framework and expand the practical applications of piezotronics and piezo-phototronics in functional nanodevices and nanosystems.