Development and prospects of nitride materials and devices with nonpolar surfaces

The quest to use nonpolar surfaces of nitride materials and devices started a few years ago with the aim to avoid the strong internal electric fields in active regions of optoelec‐tronic devices and to improve their efficiency. Starting with the growth optimizations, the progression via thorough understanding of new physical properties of the materials has led to significant improvement of device performance and to novel device concepts. In this review a historical survey of nonpolar nitride growth achievements is made. Along the way new challenges in material growth and characterization have been encountered and more sophisticated methods have been developed, which are briefly summarized. The main properties of the nitride materials grown in nonpolar directions are discussed with emphasis on the deviations from those of nitrides grown along the polar direction. Physical phenomena such as inherently present anisotropic in‐plane strain and optical polarization anisotropy have been proposed for the realization of novel polarized light‐emitting diodes, polarization‐sensitive detectors and modulators. The present status of the nitride devices with nonpolar and semipolar surfaces is discussed, and an outlook of the future trends is presented. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)