ABSTRACT
Improvements in crystal growth techniques overcoming the lattice-mismatch with the substrate and attaining an appropriate conductivity, made possible a drastic development of optical and electronic properties of GaN-based semiconductors [1-4]. Light emitting diodes and laser diodes in an ultraviolet (UV) or near UV wavelength region have proven their high efficiency and reliability, widening their field of applications toward those of conventional light bulbs. Better durability of GaN-based transistors against high temperature and/or intense radiation than those based on GaAs made them promising to attain such high power operation under hard environment, as required for applications in satellite technology.
