Ohmic Contact With a Contact Resistivity of 12 Ω ⋅ <i>mm</i> on p-GaN/AlGaN/GaN

Abstract

A robust ohmic contact process with ultralow contact resistivity on p-GaN/AlGaN/GaN is demonstrated. An in-situ removal of GaO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">X</sub> interfacial layer after contact metal deposition is developed. Using the novel Mg/Pt/Au stack as the contact metal, a stable ohmic contact is obtained after 450°C/300 s annealing with ohmic contact resistivity of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$12 \Omega \cdot {\mathrm {mm}}$ </tex-math></inline-formula> ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$1.8\times 10^{-5}\, \Omega \cdot {\mathrm {cm}}^{2}$ </tex-math></inline-formula> ). A new ohmic contact formation mechanism on p-GaN/AlGaN/GaN is also proposed.