Effect of ammonification temperature on the formation of coaxial GaN/Ga2O3 nanowires

The effect of ammonification temperature on the formation of coaxial GaN/Ga2O3 nanowires from beta-Ga2O3 nanowires is reported in this work. High quality wurtzite GaN material showing a single c-plane phase is achieved from beta-Ga2O3 nanowires having monoclinic crystal structure at a high ammonification temperature of 1050 degrees C. Lower ammonification temperatures such as 900 degrees C are also adequate for achieving coaxial GaN/Ga2O3 nanowire heterostructures, and the degree of GaN phase can be adjusted by varying the ammonification temperature. The crystalline quality of GaN/Ga2O3 nanowires improves with increasing the ammonification temperature. Resonant Raman spectra of GaN/Ga2O3 nanowires show Raman progression through multiple longitudinal-optical-phonon modes with overtones of up to second order. The development and improvement of the emission peak toward the near band edge of GaN at different ammonification temperatures were investigated using cathodoluminescence and photoluminescence characterization.