2. Piezopotential in Wurtzite Semiconductors

The most fundamental physics for piezotronics and piezo-phototronics is in the presence of a piezoelectric potential (piezopotential) in semiconductor structured materials, such as the wurtzite structure. This chapter introduces the fundamental theory for calculating the piezopotential distribution in nanostructures with and without considering the presence of doping. The finite conductivity possessed by the material can partially screen the regional piezopotential having an opposite polarity to the type of doping, but cannot completely cancel the polarization charge due to the dielectric property of the material and the moderate doping level. The effect of piezopotential on the local contact in electrical measurements is also discussed, and a through-end model is proposed for understanding the transport properties of nanowire-based devices. This model will be adopted in future chapters for understanding the I–V characteristics of the devices.