Size- and temperature-dependent piezoelectric properties of gallium nitride nanowires

The piezoelectric constant e33 is calculated using molecular dynamic simulations for square gallium nitride (GaN) nanowires (NWs). Its magnitude is found to decrease significantly with increasing cross-section and temperature. An attempt is made to understand the physics behind the size- and temperature dependence of e33. Specifically, a constant surface piezoelectric coefficient e33s=0.52×10-9C/m is achieved for square GaN NWs independent of the geometric size of their cross-sections.