Comprehensive Annealing Effects on AlGaN/GaN Schottky Barrier Diodes With Different Work-Function Metals

In this article, we have systematically investigated the effect of annealing of fabricated GaN Schottky barrier diodes (SBDs) and anode metals with various work-functions on the performance of AlGaN/GaN SBDs. It is found that after annealing of fabricated GaN SBDs, the interface states between the metal and GaN etching surface are suppressed, the device stability is enhanced, and the turn-on voltage (${\mathrm {V}}_{ \mathrm{\scriptscriptstyle ON}}$) shows negligible degradation. Meanwhile, high-performance AlGaN/GaN SBDs with various work-function metals as anode have been achieved by adapting the annealing treatment. The calculated Schottky barrier heights of the fabricated SBDs with Cr, W, and Ni anode is 0.27, 0.68, and 0.98 eV, respectively, which are almost the same as those estimated from XPS measurements. A low turn-on voltage of 0.42 V and low leakage current of$0.3~\mu \text{A}$/mm are obtained by using the low work-function metal W (4.6 eV) as anode. Furthermore, the SBDs fabricated with the high work-function metal Ni (5.1 eV) shows an extremely low-leakage current of 6 nA/mm and exhibit a current ON/OFF ratio of$10^{{9}}$while also showing great characteristics at high temperature.