Multi-Channel Tri-Gate GaN Power Schottky Diodes With Low ON-Resistance

In this letter, we demonstrate high-performance lateral GaN power Schottky barrier diodes based on a novel multi-channel tri-gate architecture. A significant reduction in ON-resistance ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${R}_{ \mathrm{\scriptscriptstyle ON}}$ </tex-math></inline-formula> ) of 50%, down to <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$7.2 \pm 0.4~\Omega \cdot {\mathrm {mm}}$ </tex-math></inline-formula> , along with a much smaller forward voltage ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${V}_{\mathrm {F}}$ </tex-math></inline-formula> ) of 1.57 ± 0.06 V, were achieved with multiple 2DEG channels (multi-channels) formed by periodic AlGaN/GaN heterostructures. We used a tri-anode structure to form Schottky contact to the multi-channels through the fin sidewalls, leading to a small turn- ON voltage ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${V}_{ \mathrm{\scriptscriptstyle ON}}$ </tex-math></inline-formula> ) of 0.67 ± 0.04 V. To simultaneously control the multi-channels and effectively spread the electric field in OFF state, a tri-gate structure was integrated in the anode, resulting in an ultra-low leakage current ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${I}_{\mathrm {R}}$ </tex-math></inline-formula> ) of ~1 nA/mm at −600 V and a high breakdown voltage ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${V}_{\mathrm {BR}}$ </tex-math></inline-formula> ) of −900 V at <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$1~\mu$ </tex-math></inline-formula> A/mm with grounded substrate. In addition, the devices presented promising switching performance, due to the small product of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${R}_{ \mathrm{\scriptscriptstyle ON}}$ </tex-math></inline-formula> and reverse charge ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${Q}$ </tex-math></inline-formula> ), thanks to the optimized tri-gate geometry, and high effective mobility ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu _{\mathrm {e}}$ </tex-math></inline-formula> ) of 2063 ± 123 cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\cdot $ </tex-math></inline-formula> V <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">−1</sup> s <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">−1</sup> despite the small fin width ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${w}$ </tex-math></inline-formula> ) of 50 nm. Our approach combines in a unique way the excellent electrostatic control of the tri-gate structure with the high conductivity of multi-channels, offering a promising platform for future advances in GaN power devices.