Ohmic Contact to <i>p</i>-Type GaN Enabled by Post-Growth Diffusion of Magnesium
Jia Wang, Shun Lu, Wentao Cai, Takeru Kumabe, Yuto Ando, Yaqiang Liao, Yoshio Honda, Ya‐Hong Xie, Hiroshi Amano
Abstract
We demonstrated the formation of excellent Ohmic contact to <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${p}$ </tex-math></inline-formula> -type GaN (including the plasma etching-damaged <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${p}$ </tex-math></inline-formula> -type GaN which otherwise exhibited undetectable current within ±5 V) by the post-growth diffusion of magnesium. The specific contact resistivity on the order of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$10^{-{4}}\,\,\Omega $ </tex-math></inline-formula> .cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> (extracted at V = 0 V) was achieved on the plasma-damaged <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${p}$ </tex-math></inline-formula> -GaN with linear current-voltage characteristics by the transfer length method (TLM) measurement. The improvement in current by a factor of over 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">9</sup> was also obtained on the plasma-damaged <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">p-n</i> junction diode after the same Mg-treatment. These experimental results indicate a great potential of post-growth diffusion of Mg to overcome the bottleneck of forming a good Ohmic contact to <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${p}$ </tex-math></inline-formula> -GaN.