Evaluation of lattice displacement in Mg – Implanted GaN by Rutherford backscattering spectroscopy

Abstract Evaluation of lattice displacement in Mg-ion implanted GaN is studied by combining elastic recoil detection analysis (ERDA), Rutherford backscattering spectroscopy (RBS) and Photoluminescence (PL) measurements. Mg-ion implantation into GaN single crystal wafer is performed with energies of 30 keV (ion fluence; 3.5 × 10 14  cm −2 ) and 60 keV (6.5 × 10 14  cm −2 ) at room temperature. The ERDA measurements using the 1.5 MeV helium beam can evaluate hydrogen from the surface to ∼300 nm. The hydrogen concentration for un-implanted and as-implanted GaN is 3.1 × 10 14  cm −2 and 6.1 × 10 14  cm −2 at around 265 nm in depth. χ min (the ratio of aligned and random yields) near the surface of the 〈0 0 0 1〉 direction for Ga is 1.61% for un-implanted and 2.51% for Mg-ion implanted samples. On the other hand, the value of χ min for N is 10.08% for un-implanted and 11.20% for Mg-ion implanted samples. The displacement concentration of Ga and N estimated from these χ min values is 4.01 × 10 20  cm −3 and 5.46 × 10 20  cm −3 , respectively. This suggests that Ga vacancy (V Ga ), N vacancy (V N ), Ga interstitial (Ga i ), and N interstitial (N i ) is introduced in Mg-ion implanted GaN. A strong emission at around 400 nm in as-implanted GaN is related to a V N donor and some acceptor pairs. It is suggested that the origin of the very high resistivity after the Mg-ion implantation is attributed to the carrier compensation effect due to the deep level of N i as a non-radiative center.