METALORGANIC VAPOR-PHASE EPITAXY GROWTH AND CHARACTERISTICS OF MG-DOPED GAN USING GAN SUBSTRATES

The homoepitaxial GaN:Mg was grown on GaN/ZnO/sapphire subtrates at various temperatures (1050-110 degrees C) by metalorganic vapor phase epitaxy (MOVPE). The GaN layers were hundreds of micrometers thick and prepared by hydride vapor phase epitaxy (HVPE) using sapphire substrates with ZnO buffer layers. The epitaxial layers showed strong blue light emitting intensity and the red shifts (400 to 445 nm) of their CL spectra were observed as the growth temperatures became higher. The same red-shifted phenomenon was also confirmed for the heteroepitaxial layers on the sapphire substrates. These results imply that more blue emission centers related to Mg are formed as the growth temperature grow higher. The blue-light emitting diodes of GaN:Mg/GaN, utilizing n-type GaN substrate which were hundreds of micrometers thick, were fabricated for the first time using electrodes on the back surface of electroconductive GaN substrates. The electroluminescence spectra of the light emitting diode (LED) revealed blue-light emission peaking at 430 nm. The current rectification of I-V characteristics suggests that the emission originates from p-n junction.