Lattice disorder in neutron irradiated GaN: Nuclear reaction analysis and Rutherford backscattering studies

Disorders of N and Ga lattice in GaN, introduced by fast neutron irradiation with a fluence of 6.7 x 10(18) cm(-2), are investigated by nuclear reaction analysis (NRA) using 14 N(d, P)15 N reaction with 2.6 MeV D-2(+) ions and by Rutherford backscattering (RBS) with 1.5 MeV He-4(+) ions. The (0001) aligned NRA yield measured in as-irradiated GaN slightly increases compared with that of un-irradiated crystals, indicating that primary knock-on (PKO) produced by the neutrons results in similar to 7.2 x 10(2) displaced N atoms. The slight increase in the aligned RBS yield for as-irradiated samples relative to that of un-irradiated ones indicates that the similar to 1.8 x 10(2) displaced Ga atoms are produced by PKO. The displacement of N atoms is four times larger than that of Ga atoms, reflecting the lighter weight of N than Ga, although both the displacements are recovered by annealing over 1000 degrees C. The displacement of Ga atoms in GaN is two times smaller than that in GaP (similar to 3.0 x 10(2) atoms/PKO), showing the stronger bonds in GaN than GaP. (c) 2006 Elsevier B.V. All rights reserved.