I‐V and C‐V characteristics of rare‐earth‐metal/p‐GaN Schottky contacts

The electrical properties of rare‐earth‐metal Schottky contacts to p‐GaN were characterized with current‐voltage (I‐V) and capacitance‐voltage (C‐V) measurements for the first time. Three kinds of rare‐earth‐metal films of Dy, Er, and Gd, which have low‐metal‐work‐function nature, were deposited on low‐Mg‐doped p‐GaN. Linear regions of more than one and a half orders were seen in a forward semi‐log I‐V plot, and reverse break down voltages were as high as around 60 V for all samples. In the C‐V characteristics, good linearity was obtained in a 1/C 2 plot for all samples. The carrier concentration was estimated to be about 5.5×10 16 cm –3 , which is a reasonable value of activation efficiency of 4.2%. The Schottky barrier heights of Dy, Er, and Gd contacts were 1.91, 2.38, and 2.16 eV from I‐V, and 1.79, 1.78, and 1.70 eV from C‐V, respectively. These values are as high as those of the transition metal contacts. These results tell us that Fermi level pinning is significantly strong for p‐GaN surfaces with a conventional acid treatment. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)