A perspective on piezotronics and piezo-phototronics based on the third and fourth generation semiconductors

The rapid development of semiconductor materials and devices has brought tremendous development opportunities to optoelectronics, intelligent manufacturing, Internet of Things, power electronics, and even innovative energy technologies. Among them, the third and fourth generation semiconductors represented by ZnO, GaN, SiC, and Ga2O3 are two kinds of emerging strategic material systems. Due to their large energy bandgaps, they exhibit excellent performance in application scenarios of high voltage, high frequency, and high temperature resistance, making them great candidates in high-power, radio frequency, and optoelectronic devices. The third and fourth generation semiconductors usually possess non-centrosymmetric crystal structures, which makes the piezoelectric polarization effect a fundamental characteristic for the third and fourth generation semiconductors in contrast to the first and second generation semiconductors as represented by Si, Ge, and GaAs. Research studies on the coupling of piezoelectricity, semiconductor, and light excitation properties were coined as piezotronics and piezo-phototronics in 2007 and 2010, respectively, by Zhong Lin Wang. The piezotronic and piezo-phototronic effects open another avenue for further improvement of the performance of electronic and optoelectronic devices. This Perspective will first introduce the basic concepts and principles of piezotronics and piezo-phototronics and the basic characteristics of the third and fourth generation semiconductors. Then, progress, challenges, and opportunities of ideal materials, comprehensive physical models, and outstanding applications based on piezotronics and piezo-phototronics are presented with emphasis. Finally, conclusions and outlooks are drawn for the piezotronics and piezo-phototronics based on the third and fourth generation semiconductors.