Researchers at Georgia Institute of Technology have used zinc oxide (ZnO) microwires to significantly improve the efficiency at which gallium nitride (GaN) LEDs convert electricity to ultraviolet light. The devices are believed to be the first LEDs whose performance has been enhanced by the creation of an electrical charge in a piezoelectric material using the piezo-phototronic effect. The research was sponsored by the Defense Advanced Research Projects Agency (DARPA) and the U.S. Department of Energy (DOE). By applying mechanical strain to the microwires, researchers at the university created a piezoelectric potential in the wires, and that potential is used to tune the charge transport and enhance carrier injection in the LEDs. This control of an optoelectronic device with piezoelectric potential, known as piezo-phototronics, represents another example of how materials that have both piezoelectric and semiconducting properties can be controlled mechanically.
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