[1] Nakamura S, Mukai T, Senoh M. Candela-class high-brightness InGaN/AlGaN double-heterostructure blue-light-emitting diodes$$J$$. Appl. Phys. Lett., 1994, 64: 1687-1689.

[2] Nakamura S, Senoh M, Iwasa N, et al. Superbright green InGaN single-quantum-well-structure light-emitting diodes$$J$$. Jap. J. of Appl. Phys., 1995, 34: L1332-L1335.

[3] Pearton S J, Zolper J C, Shul R J, et al. GaN: Processing, defects, and devices$$J$$. J. of Appl. Phys., 1999, 86: 1-78.

[4] Luther B P, Mohney S E, Jackson T N, et al. Investigation of the mechanism for ohmic contact formation in Al and Ti/Al contacts ton-type GaN$$J$$. Appl. Phys. Lett., 1997, 70: 57-59.

[5] Tseng C L, Youh M J, Moore G P, et al. Mechanism for the increased light transmission through Ni/Au/ZnO contacts on p-GaN for high power optoelectronic devices$$J$$. Appl. Phys. Lett., 2003, 83(18): 3677-3679.

[6] Cho H K, Hossain T, Bae J W, et al. Characterization of Pd/Ni/Au ohmic contacts on p-GaN$$J$$. Solid-State Electron., 2005, 49: 774-778.

[7] Song J O, Leem D S, Kwak J S, et al. High-quality nonalloyed rhodium-based ohmic contacts to p-type GaN$$J$$. Appl. Phys. Lett., 2003, 83: 2372-2374.

[8] Zhang N, Xu F J, Lang J, et al. Improved light extraction efficiency of AlGaN deep-ultraviolet light emitting diodes combining Ag-nanodots/Al reflective electrode with highly transparent p-type layer$$J$$. Opt. Express, 2021, 29: 2394-2401.

[9] Chen W, Zhou Y, Yu X, et al. The effect of the original thickness of Ag in the graphene-Ag nanodots transparent conductive layer on the electrical and optical properties of GaN-based UV-LEDs$$J$$. IEEE Trans. on Electron Devices, 2018, 65: 3803-3808.

[11] Pan S, Lu Y, Liang Z, et al. Optimization of annealing conditions for Ag/p-GaN ohmic contacts$$J$$. Appl. Phys. A: Mater. Sci. Process, 2021, 127: 870.

[12] Lin N M, Shei S C, Chang S J. Investigation of Ni/Ag contact to p-GaN with an O2 plasma treatment and its application to GaN-based LEDs$$J$$. Physica Status Solidi A: Applications and Materials Science, 2012, 209: 1568-1574.

[14] Pal S, Mahapatra R, Ray S K, et al. Microwave plasma oxidation of gallium nitride$$J$$. Thin Solid Films, 2003, 425: 20-23.