[14p-PB2-1~21] 13.8 Compound and power electron devices and process technology

▲ [14p-PB2-13] Origin of ohmic contact formation on AlGaN/GaN structure grown on GaN substrate

〇Daryoush Zadeh¹, Shinichi Tanabe¹, Noriyuki Watanabe¹, Hideaki Matsuzaki¹ (1.NTT Corporation)

Keywords:AlGaN/GaN ohmic contact,GaN substrate,TLM

Forming ohmic contact with low resistance is important to maximize advantages of AlGaN/GaN HEMTs. Commonly, Al/Ti-based structures are used as the ohmic contacts for AlGaN/GaN. TiN spikes which penetrate the AlGaN layer through threading dislocations at GaN, are reported to be the mechanism for achieving ohmic contact. However, we previously reported Au/Mo/Al/Ti ohmic contacts with low contact resistivity on AlGaN/GaN structures grown on free-standing GaN substrate, in which threading dislocation density is only 0.1% that of AlGaN/GaN grown on Si substrate. In this work, we investigate the mechanism behind achieving low resistivity ohmic contacts on AlGaN/GaN structures with low threading dislocation density.