ATOMIC GEOMETRY AND ELECTRONIC-STRUCTURE OF NATIVE DEFECTS IN GAN

We have studied the electronic structure, atomic geometry, and formati on energies of native defects in GaN using first-principles total-ener gy calculations. Our results reveal the vacancies to be the dominant d efects in GaN, whereas antisites and interstitials are energetically l ess favorable. Inp-type GaN the nitrogen vacancy (a donor) has the low est formation energy, in n-type GaN the gallium vacancy (an acceptor). Our results show that the vacancies may be important for compensation . However, isolated point defects and particularly the nitrogen vacanc y can be excluded as the source for the n-type conductivity in as-grow n GaN, contrary to the generally accepted picture.