Effects of Phosphorus Implantation on the Activation of Magnesium Doped in GaN

Abstract

The effects of phosphorus implantation on the activation of magnesium doped in GaN at different dopant concentration ratios have been systematically investigated. Hall effect measurements show that P implantation improves the hole concentration, and that this improvement is dependent on P/Mg dopant concentration ratio and annealing conditions. This phenomenon is attributable to the reduction in selfcompensation that results from the formation of deep donors and the enhanced Mg atom activation, which is in reasonable agreement with the optical properties observed by photoluminescence measurements. In addition, a new photoluminescence peak resulting from P-related transitions is also observed, evidently owing to the recombination of electrons from the shallow native donors with holes previously captured by isoelectronic P traps. #

Phosphorus implantation of Mg-doped (Al)GaN heterostructures: structural examination and depth profiling

“…An analogous situation occurs for P-implanted AlGaN:Mg at the surface the ratio P/Mg * 0.1, while for standardized depth of 75%, P/Mg = 2. Thus, these results confirm that an appropriate ratio of P to Mg across the (Al)GaN layers is needed to achieve relatively good p-type conductivity [8,9]. Importantly, a certain amount of Mg in the doped AlGaN structures is a key aspect influencing the electrical parameters.…”

“…To achieve such effect it is necessary to keep the P/Mg ratio = 0.01-reducing this ratio results in a deterioration of hole concentration (to 6.2 9 10 16 cm -3 for the ratio P/Mg = 0.001). Probably the main reason for such a drastic deterioration of the electrical properties is an inadequate ratio of P/Mg, according to the work of Liu et al [8,9]. The SIMS results showed that for P-implanted GaN:Mg the ratio P/Mg at the surface is about 0.1, but deeper into the sample (* 25%) this ratio significantly changes and is approximately 100.…”

“…It was revealed that the higher the amount of dopant implanted into the structure, the more noticeable is the increase in hole concentration, varies from 10 10 to 10 12 cm -2 for a dose of co-implanted ions from 2 9 10 14 to 5 9 10 15 cm -2 , respectively [4]. The annealing temperature affects not only Liu et al showed also that annealing of P-implanted and Mg-doped GaN at relatively high temperatures (1200°C) allows producing p-type conductivity with a hole concentration of 6.9 9 10 17 cm -3 and mobility of 12 cm 2 V -1 s [8,9]. To achieve such effect it is necessary to keep the P/Mg ratio = 0.01-reducing this ratio results in a deterioration of hole concentration (to 6.2 9 10 16 cm -3 for the ratio P/Mg = 0.001).…”

“…P) [8] 0.01 6.9 9 10 17 -1 2 GaN:(Mg ? P) [9] 0.01 2.1 9 10 17 3.6 8.2 GaN:(Mg ? P) [9] 0.001 6.2 9 10 16 10.7 9.5 Co-impl.…”

“…Mg is the most frequently used element to obtain a p-type conductivity [6], but its concentration in AlGaN structures is still too low. This issue is related to the large ionization energy of Mg acceptor, which limits the number of holes in AlGaN structure [7][8][9]. Post-implantation annealing is one of the problems that also appear during ion implantation processes in GaNbased heterostructures.…”