The effect of nitrogen ion damage on the optical and electrical propertiesof MBE GaN grown on MOCVD GaN/sapphire templates

We have established a correlation between localized states responsible for mid-gap optical emission and film mobility of GaN grown under different nit rogen conditions. By imposing a deflector voltage at the tip of the plasma source, we varied the ion/neutral flux ratio to determine how N ions affect mid-gap luminescence and electrical mobility. Low energy electron-excited nanometer scale luminescence (LEEN) spectroscopy in ultrahigh vacuum (UHV) showed mid-gap emission intensities in the bulk that decreased in the ratio , 50 : 1.3 : 1 with increasing deflector voltage. Hall measurements indicat ed over a factor of two increase in mobility, and a factor of 8 decrease in residual charge density with increasing deflector voltage. The correlation of optical and electrical properties with a reduction in N ion flux sugges ts the primary role of native defects, such as N or Ga vacancies, in the mi d-gap emissions.