Departmental Bulletin Paper Microstructures Observation of N-type GaN Contacts and the Electrical Properties

Maeda, Masakatsu  ,  Takahashi, Yasuo  ,  Halil Aiman bin Mohd  ,  Kimura, kota

44 ( 1 )  , pp.19 - 22 , 2015-06 , 大阪大学接合科学研究所 , Joining and Welding Research Institute, Osaka University , オオサカ ダイガク セツゴウ カガク ケンキュウジョ
In the present study, to increase the carrier density of n-GaN, the formation of N-vacancies are attempted by interfacial reaction and by Ar ion irradiation. The microstructure and electrical properties after the interfacial reaction and Ar ion irraddiation were then analyzed by TEM and DC conduction tests. The TEM result indicates that Ti2N is formed adjacent to the GaN substrate after the desposition of Ti film. theTi2N formation indicated that a huge amount of N-vacancies is formed within the subsurface of GaN. The electrical conduction profile reveals that even with the formation of Ti2N, ohmic conduction ia achieved. It is likely due to the formation of N-vacancies by interfacial reaction to form Ti2N and Ar ion irradiation. By prolonging the Ar ion irradiation, further improvement of electrical conductivity is achieved. This result indicated that the amount of N-Vacancies formation within the GaN subsurface are depending to the Ar ion irradiation times. Howevers, by performing Ar ion irradiation for 3600s, no futher improvement is achieve. It is likely due to phase transformation from GaN to Ga-rich phase at the GaN subsurface. The Ga-rich phase enhance the Ga-Ti compound, which increase the height and width of the Schottky barrier, thus reduce th electrical conductivity.

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