Si-implantation for low ohmic contact resistances in RF GaN HEMTs
H. Yazdani, F. Brunner, A. Thies, H.J. Würfl and O. Hilt
Published in:
Semicond. Sci. Technol., vol. 39, no. 10, pp. 105003, doi:10.1088/1361-6641/ad70d5 (2024).
Abstract:
In this work, Si implantation and activation for lowering the ohmic contact resistance (Rc) of mm-wave GaN HEMTs has been investigated. Various combinations of annealing temperature/duration and implantation doses were tested. Dopant activation was performed using a modified procedure in an MOCVD tool, involving fast temperature ramping and annealing the samples for 8 min at 1150°C. Thereby, ∼0.02 ± 0.01 Ω mm contact resistance was achieved on a fully doped region and ∼0.1 ± 0.02 Ω mm when only the source and drain contact region was n-type doped. For comparison, a well-established alloyed Ti/Al/Ni/Au ohmic contact scheme without implantation, was used as reference resulting in an average Rc ∼0.34 ± 0.12 Ω mm on the same wafer. Besides the three times lowered contact resistance the implanted contacts also showed a significantly improved on-wafer homogeneity.
Ferdinand-Braun-Institut, Leibniz-Institut für Höchstfrequenztechnik (FBH), Berlin, Germany
Keywords:
GaN HFETs, two-dimensional electrons gas (2DEG), contact resistance
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