Substitutional diffusion of Mg into GaN from GaN/Mg mixture

Abstract

We evaluated Mg diffusion into GaN from GaN/Mg mixture. The diffusion depth of Mg increased with diffusion temperature from 1100 °C to 1300 °C, whereas the Mg concentration remained constant at 2–3×10^18 cm^-3 independent of temperature. The estimated activation energy for Mg diffusion was 2.8 eV, from which the substitutional diffusion mechanism was predicted. Mg-diffused GaN samples showed p-type conductivity with a maximum hole mobility of 27.7 cm^2V^-1s^-1, suggesting that substitutional diffusion contributes to Mg activation. This diffusion technique can be used to easily form p-type GaN and has potential as a p-type selective doping technique.

Pressure Effect on Diffusion of Native Defects and Mg Impurity in Mg‐Ion‐Implanted GaN during Ultrahigh‐Pressure Annealing

“…This speculation is based on a previous study suggested that applying hydrostatic pressure enhances Frenkel‐pair‐like annihilations of point defects in gamma‐irradiated Si and GaAs. [ 5 ] Moreover, since the Mg Ga concentration in Figure 1b (1 to 3 × 10 18 cm −3 ) agrees with the maximum concentrations of Mg in GaN doped by thermal diffusion, [ 12,35,36 ] the difference between the Mg Ga concentration at 2.0 GPa and that at 0.3 GPa indicates that the maximum concentration or solubility could be changed by the hydrostatic pressure.…”

Observation of 2D-magnesium-intercalated gallium nitride superlattices

“…However, annealing at temperatures higher than 1,000 °C requires a masking layer to prevent incongruent decomposition of GaN. Furthermore, annealing at temperatures of more than 1,000 °C favours substitutional diffusion of Mg 55 , which could lead to thermal instability of the superlattice structure and decomposition of the interstitial Mg sheets. Temperatures lower than 550 °C might be possible but could require much longer annealing times 45 .…”

Ga-polar GaN Camel diode enabled by a low-cost Mg-diffusion process

“…Recently, we have shown that Mg diffusion into GaN follows an exponentially decaying concentration profile; effective doping is highest at the surface. 33,37,38) For the case of 800 °C annealing, a peak surface Mg concentration of ∼3 × 10 21 cm −3 was observed with secondary ion mass spectrometry (SIMS). 33) However, only a fraction of the Mg concentration was observed to act as a substitutional dopant.…”

“…In recent years, we have shown that the Mg diffusion process is a low-cost technology for acceptor-type doping of GaN. 37) The Mg diffusion process has been further utilized to realize low-resistance ohmic contacts to p-GaN 33) and highly efficient p-GaN SBDs. 38) At present, understanding the Mg diffusion process in GaN is still at the embryonic stage.…”