High Mg activation in implanted GaN by high temperature and ultrahigh pressure annealing

Abstract

We demonstrate high p-type conductivity and hole concentrations >1018 cm−3 in Mg-implanted GaN. The implantation was performed at room temperature and by post-implantation annealing at 1 GPa of N2 and in a temperature range of 1200–1400 °C. The high pressure thermodynamically stabilized the GaN surface without the need of a capping layer. We introduce a “diffusion budget,” related to the diffusion length, as a convenient engineering parameter for comparing samples annealed at different temperatures and for different times. Although damage recovery, as measured by XRD, was achieved at relatively low diffusion budgets, these samples did not show p-type conductivity. Further analyses showed heavy compensation by the implantation-induced defects. Higher diffusion budgets resulted in a low Mg ionization energy (∼115 meV) and almost complete Mg activation. For even higher diffusion budgets, we observed significant loss of Mg to the surface and a commensurate reduction in the hole conductivity. High compensation at low diffusion budgets and loss of Mg at high diffusion budgets present a unique challenge for shallow implants. A direct control of the formation of compensating defects arising from the implantation damage may be necessary to achieve both hole conductivity and low Mg diffusion.

Design and demonstration of nearly-ideal edge termination for GaN p–n junction using Mg-implanted field limiting rings

“…For N a = 2.8 × 10 17 cm −3 , we obtain R = N a /[Mg] = 2.8 × 10 17 cm −3 /(2.9 × 10 17 cm −3 ) ≈ 96.6%, which is consistent with those reported previously. 23,27,28,31) Furthermore, Fig. 5(c) indicates that by the suitable optimization of N a , a BV of more than 650 V can be realized without FLRs, which has already been demonstrated experimentally.…”

Closing the yellow gap with Eu- and Tb-doped GaN: one luminescent host resulting in three colours

“…But here again it´s not about photoluminescence. Mg doping in relation with GaN:Eu has been investigated by several other groups as well 47 – 51 , as the Mg co-doping is supposed to increase the photoluminescence (PL) as well as the electroluminescence intensity. Hoang 52 investigated defect physics of Eu-doped GaN using first-principles hybrid density-functional.…”

Effects of Hydrogen Incorporation on Mg Diffusion in GaN‐Doped with Mg Ions via Ultra‐High‐Pressure Annealing

“…Using this technique, the implantation-induced strain is effectively removed, [12] and high acceptor activation percentages greater than 80% respective to implanted magnesium (Mg) ions have been obtained. [10,13,14] Unfortunately, prolonged annealing at high temperatures can promote the diffusion of Mg atoms so that the dopant dispersion profile is changed. [10,[13][14][15] Sakurai et al [15] reported that the diffusion coefficient for Mg atoms in GaN was 30 times larger than that for Mg in epitaxially grown Mg-doped GaN.…”

“…[10,13,14] Unfortunately, prolonged annealing at high temperatures can promote the diffusion of Mg atoms so that the dopant dispersion profile is changed. [10,[13][14][15] Sakurai et al [15] reported that the diffusion coefficient for Mg atoms in GaN was 30 times larger than that for Mg in epitaxially grown Mg-doped GaN. This finding suggests that dopant diffusion is enhanced by the formation of point defects during implantation.…”

“…Using this technique, the implantation‐induced strain is effectively removed, [ 12 ] and high acceptor activation percentages greater than 80% respective to implanted magnesium (Mg) ions have been obtained. [ 10,13,14 ]…”