Gate-First AlGaN/GaN HEMT Technology for High-Frequency Applications
Author(s)Piner, Edwin L.; Chung, Jinwook; Saadat, Omair Irfan; Palacios, Tomas
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This letter describes a gate-first AlGaN/GaN high-electron mobility transistor (HEMT) with a W/high-k dielectric gate stack. In this new fabrication technology, the gate stack is deposited before the ohmic contacts, and it is optimized to stand the 870degC ohmic contact annealing. The deposition of the W/high-k dielectric protects the intrinsic transistor early in the fabrication process. Three different gate stacks were studied: W/ HfO[subscript 2], W/Al[subscript 2]O[subscript 3], and W/HfO[subscript 2]/Ga2O[subscript 3]. DC characterization showed transconductances of up to 215 mS/mm, maximum drain current densities of up to 960 mA/mm, and more than five orders of magnitude lower gate leakage current than in the conventional gate-last Ni/Au/Ni gate HEMTs. Capacitance-voltage measurements and pulsed-IV characterization show no hysteresis for the W/HfO[subscript 2]/ Ga2O[subscript 3] capacitors and low interface traps. These W/high-k dielectric gates are an enabling technology for self-aligned AlGaN/GaN HEMTs, where the gate contact acts as a hard mask to the ohmic deposition.
DepartmentMassachusetts Institute of Technology. Department of Electrical Engineering and Computer Science; Massachusetts Institute of Technology. Microsystems Technology Laboratories
IEEE Electron Device Letters
Institute of Electrical and Electronics Engineers
Saadat, O.I. et al. “Gate-First AlGaN/GaN HEMT Technology for High-Frequency Applications.” Electron Device Letters, IEEE 30.12 (2009): 1254-1256. ©2009 Institute of Electrical and Electronics Engineers.
Final published version
self-aligned, high-electron mobility transistor (HEMT), high-k dielectric, GaN