Characterizations of Beryllium Implanted Mg-doped GaN
Dr. S. C. Wang
Dr. W. K. Chen
Abstract We investigated the characteristics of beryllium implanted Mg-doped p-type GaN. P-type GaN samples were grown on sapphire substrate by metalorganic chemical vapor deposition. These samples were implanted with Be ions for two different doses of 1013 and 1014 cm-2 at different energies of 50 and 150 keV. Photoluminescence measurement was conducted on these implanted samples. After implantation, the luminescence characteristic of Mg dopant still dominates the spectra. Additionally, a broad emission was observed at ∼520 nm and attributed to additional lattice disorders induced by ion implantation. Moreover, a strong recovery of the 520 nm line occurred at annealing temperature of 1100℃ for 60s. Using temperature dependence PL measurement, we estimated the Mg activation energy of about 165meV, which was lower about 30% than the un-implanted samples. The implanted samples also showed an increase from 4.39×1016 cm-3 for as-grown GaN to 1.77×1019 cm-3 at annealing temperature of 1100 oC for 60sec. These results indicated that Be implantation cause lowering of Mg activation energy and increasing the carrier concentration. We measured metal-semiconductor Ni/Pd/Au ohmic contact specific resistivity and the low value of the specific resistivity was obtained to 4.5*10-6 Ω-cm2.
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