Dresden 2014 – wissenschaftliches Programm
HL 19.9: Vortrag
Montag, 31. März 2014, 17:00–17:15, POT 151
A comparative study of V/Al/Ni/Au and Ti/Al/Ni/Au ohmic contacts on n-AlGaN/GaN — •Christopher Schröter1, Alexander Schmid1, Volker Klemm2, and Johannes Heitmann1 — 1Institute of Applied Physics, TU Bergakademie Freiberg, 09599 Freiberg — 2Institute of Materials Science, TU Bergakademie Freiberg, 09599 Freiberg
A study of ohmic contact formation by V/Al/Ni/Au and Ti/Al/Ni/Au on n−Al0.23Ga0.77N/GaN heterostructures is presented. Vanadium was chosen as a potential alternative for titanium due to lower annealing temperatures required for the ohmic contact formation. For the V/Al/Ni/Au metallization low resistance ohmic contacts were achieved after annealing at 650∘C for 30 s. This is a reduction of 150 K compared to the reference Ti/Al/Ni/Au stack. The minimum measured specific contact resistivity was 2.3*10−6 Ωcm2 at an annealing temperature of 800∘C and 2*10−5 Ωcm2 at an annealing temperature of 650∘C. A variation of the vanadium layer thickness from 35 nm to 15 nm showed an improved contact formation for the thinner layer.
After annealing the V/Al/Ni/Au metallization exhibited sharper edges and smoother surfaces compared to the rough Ti/Al/Ni/Au reference stack. For further investigation of the contact microstructure, transmission electron microscopy (TEM), electron energy loss spectroscopy (EELS) and energy dispersive x-ray diffraction (EDX) measurements were performed.