Band structure engineering at heterojunction interfaces via the piezotronic effect.

Engineering the electronic band structure using the piezopotential is an important aspect of piezotronics, which describes the coupling between the piezoelectric property and semiconducting behavior and functionalities. The time-independent band structure change under short-circuit condition is believed to be due to the remnant piezopotential present at the interface, a result of the finite charge-screening depth at the interface. A series of materials, including metals, semiconductors and electrolytes, are selected to investigate the interfacial band structure engineered by remnant piezopotential when they are in contact with a strained piezoelectric semiconductor. The remnant piezopotential at the interface can switch the junction between Ohmic and Schottky characters, enhance charge combination/separation, regulate barrier height, and modulate reaction kinetics. The difference between the regular time-dependent, pulse-type piezopotential and constant remnant piezopotential is also discussed in detail using a ZnO-based photoelectrochemical anode as an example. The piezotronic effect offers a new pathway for engineering the interface band structure without altering the interface structure or chemical composition, which is promising for improving the performance of many electronics, optoelectronics, and photovoltaic devices.