In this paper, we present a normally-off GaN-based transistor with extremely low on-state resistance fabricated by using Ge-doped n++GaN layer for ohmic contact. We developed a new GaN regrowth technique using Ge, which achieved extremely high doping level of 1 × 1020 cm-3, and thereby the lowest specific contact resistance of 1.5 × 10-6 Ω·cm2. Selectively deposited NiO gate using Atomic Layer Deposition (ALD) technique contributed to shorten the spacing between source and drain, making normally-off characteristics even with the 30% Al mole fraction of AlGaN. The fabricated device showed the record-breaking Ron of 0.95 Ω·mm with maximum drain current (Id,MAX) and transconductance (gm) of 1.1 A/mm and 490 mS/mm, respectively. It is noted that the obtained Vth was 0.55 V. An on/off current ratio of 5 × 106 is also achieved.
|Title of host publication||2014 IEEE International Electron Devices Meeting, IEDM 2014|
|Publisher||Institute of Electrical and Electronics Engineers Inc.|
|State||Published - 20 Feb 2015|
|Event||2014 60th IEEE International Electron Devices Meeting, IEDM 2014 - San Francisco, United States|
Duration: 15 Dec 2014 → 17 Dec 2014
|Conference||2014 60th IEEE International Electron Devices Meeting, IEDM 2014|
|Period||15/12/14 → 17/12/14|