Polarization fields of III-nitrides grown in different crystal orientations.

This article reviews the piezoelectric properties of III-nitrides with emphasis on GaN, InN, and their ternary alloys. After a short literature survey we concentrate on semipolar and nonpolar quantum wells grown on crystal planes other than the commonly used c plane ({0001}). The electrostatic field within a quantum well causes a quantum confined Stark effect and thus lowers the radiative transition probability as well as the transition energy. The basic impact of the quantum confined Stark effect on the optical properties of GaInN/GaN quantum wells is discussed in detail. Some routes to determine the magnitude of the electric field are described, and recent results are considered. The measured values are compared to published piezoelectric tensor elements.