Vacancy‐type defects and their annealing behaviors in Mg‐implanted GaN studied by a monoenergetic positron beam

Abstract

Vacancy-type defects in Mg-implanted GaN were probed using a monoenergetic positron beam. Mg ions of multiple energies (15-180 keV) were implanted to provide a 200-nmdeep box profile with Mg concentration of 4 Â 10 19 cm À3 . The major defect species of vacancies introduced by Mgimplantation was a complex between Ga-vacancy (V Ga ) and nitrogen vacancies (V N s). After annealing above 1000 8C, these defects started to agglomerate, and the major defect species became (V Ga ) 2 coupled with V N s. The defect reaction occurred between not only the defects introduced by the implantation but also the defects introduced by an excess Mg-doping. The depth distribution of vacancy-type defects agreed well with that of implanted Mg, and no large change in the distribution was observed up to 13008C annealing. Relationships between photoluminescence bands and vacancy-type defects introduced by Mg-implantation are also discussed.

Vacancy-type defects in Mg-doped GaN grown by ammonia-based molecular beam epitaxy probed using a monoenergetic positron beam

“…Because of the high kinetic energy of epithermal positrons, its annihilation characteristic is unlikely to be influenced by material properties. The observed behavior of S for p-type GaN has previously been reported, 34,36 and the decrease in the S s values can be attributed to the annihilation behavior of positrons at the surface of p-type GaN.…”

“…31,34 The localization of positrons near Mg atom at the N site (Mg Ga ) was also reported in Ref. 34. The present paper reports the result of the simulation for (Mg Ga ) 2 .…”

“…The Doppler broadening spectra for the typical cation vacancies were calculated and the results were reported in the previous works. 31,34 The localization of positrons near Mg atom at the N site (Mg Ga ) was also reported in Ref. 34.…”

Detection of deep-level defects and reduced carrier concentration in Mg-ion-implanted GaN before high-temperature annealing

“…On the other hand, Ref. 10 reported that the V Ga (V N ) 2 complexes were detected by PAS for a sample after Mg implantation before annealing. However, since the dosage was sufficiently low in the present work, a probability of formation of a defect complex should have been low.…”

“…9 However, it has been reported that defects remain in the Mg-implanted GaN layer even after high-temperature annealing on the basis of positron annihilation spectroscopy (PAS) and photoluminescence (PL) studies. 10,11 To control the electrical properties of Mg-implanted GaN, an electrical measurement should be carried out to understand the thermal behavior of the defects by starting from a sample before high-temperature annealing for the activation of Mg acceptors. We here report measurement results of the electrical properties of a Mg-implanted GaN layer on a free-standing GaN substrate before high-temperature annealing.…”