Evaluation of lattice displacement and electrical property of Zn-ion implanted GaN by Rutherford backscattering spectrometry

Abstract

The lattice displacement in Zn-ion implanted GaN single crystal wafer is evaluated by Rutherford backscattering spectrometry using proton beam and Photoluminescence measurements. Zn-ion implantation into GaN single crystal wafer is performed with energies of 300 KeV (ion fluence: 2.32 × 1014cm-2), 500 KeV (3.02 × 1014cm-2) and 700 KeV (4.65 × 1014cm-2) at room temperature. The displacement concentration of Ga and N atoms evaluated from minimum yields along <0 0 0 1> direction are 4.8 × 1021 cm−3 and 3.6 × 1021 cm−3 respectively, for as-implanted GaN and decrease to 2.3 × 1021 cm−3 and 4.7 × 1020 cm−3 by annealing in N2 ambient at 700 °C. The lattice displacement of Ga atoms for as-implanted GaN evaluated from the half-value angle of the channeling dip is 0.094 Å for Zn-implanted GaN and recovers to a value of the thermal vibrational amplitude by annealing. The intensity of Yellow Luminescence (YL) observed at around 530 nm for as-implanted GaN increases significantly compared to un-implanted ones, suggesting that gallium vacancy acceptor and nitrogen vacancy donor as origins of YL are induced by Zn-ion implantation. The YL intensity for annealed GaN is almost same as the one for un-implanted GaN. The sheet resistance is 1.04 × 102cm-2 Ω/sq. for un-implanted, 3.98 × 109cm-2 Ω/sq. for as-implanted, and 3.77cm-2 Ω/sq. for annealed GaN. The high resistance for as-implanted GaN is attributed to gallium vacancy as a compensation center. The low resistance and the decrease of YL intensity after annealing is attributed to both a shallow nitrogen vacancy and the decrease of gallium vacancy.