Catalytic Activation of Mg-Doped GaN by Hydrogen Desorption Using Different Metal Thin Layers

Abstract

The annealing of Mg-doped GaN with Pt and Mo layers has been found to effectively improve the hole concentration of such material by more than 2 times as high as those in the same material without metal. Compared with the Ni and Mo catalysts, Pt showed good activation effect for hydrogen desorption and ohmic contact to the Ni/Au electrode. Despite the weak hydrogen desorption, Mo did not diffuse into the GaN epilayer in the annealing process, thus suppressing the carrier compensation phenomenon with respect to Ni and Pt depositions, which resulted in the high activation of Mg acceptors. For the GaN activated with the Ni, Pt, and Mo layers, the blue emission became dominant, followed by a clear peak redshift and the degradation of photoluminescence signal when compared with that of GaN without metal.

Diffusion and Stability of Hydrogen in Mg-Doped GaN: A Density Functional Study

“…As H i þ is mobile, all the H i þ atoms diffuse out at temperatures above 700 C. For the HSE barriers, the dissociation of Mg-H occurs at a higher temperature of around 300 C, and the annealing temperature for complete out-diffusion increases to 800 C. The calculated annealing temperatures agree well with the temperature range of 700-800 C, which are usually used in experiments. 2,[5][6][7]9) The zero point energy of H can reduce the migration barrier by about 0.1 eV. 10) We note that the correction of about 0.1 eV to the energy barriers reduces the annealing temperature by about 50-100 C. In addition, we find that the annealing temperature is affected by the initial Mg-H concentration.…”

“…However, due to the large activation energies of Mg acceptors, [2][3][4] high doping levels and thermal annealing are commonly used to electrically activate Mg acceptors. [5][6][7][8] However, hole concentrations are still low, below 10 18 cm À3 , 7) and the doping efficiency is significantly reduced for high Mg concentrations. 8) In p-type GaN, an isolated hydrogen acts as an interstitial donor (H i þ ).…”

Semipolar (112̅2) AlGaN-Based Solar-Blind Ultraviolet Photodetectors with Fast Response

“…It is generally thought that both crystal orientation and surface polarity play significant roles in the crystal quality and the performance of optoelectronic devices. Recently, there has been considerable work done on the non-/semipolar GaN materials and devices to eliminate or reduce the polarization fields, enhance the radiative efficiency and carrier transport. − The in-plane crystal asymmetry of non-/semipolar III-nitride materials could be exploited to enhance the intrinsic polarization sensitivity so as to develop its potential application, such as the polarization-sensitive photodetectors (PSPD). ,, …”