Multi-Channel Monolithic-Cascode HEMT (MC²-HEMT): A New GaN Power Switch up to 10 kV

Abstract

This work presents a new device concept, the Multi-Channel Monolithic-Cascode high-electron-mobility transistor (MC <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> -HEMT), which monolithically integrates a low-voltage, enhancement-mode (E-mode) HEMT based on single 2DEG channel and a high-voltage, depletion-mode (D-mode) HEMT based on stacked 2DEG multi-channel. This device can exploit the low sheet resistance of the multi-channel, realize an E-mode gate control, and completely shield the gate region from high electric field. It also obviates the need for nanometer-sized fin-shaped gates used in prior multi-channel HEMTs, thus relaxing the lithography requirement. We experimentally demonstrated the multi-kilovolt AlGaN/GaN MC <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> -HEMTs on a 5-channel wafer with breakdown voltage from 3.45 kV up to over 10 kV. The 10-kV MC <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> -HEMTs show a 1.5-V threshold voltage and a <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$40\text{-m}\Omega\cdot \text{cm}^{2}$</tex> specific on-resistance, which is <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\sim 2.5$</tex> -fold smaller than that of 10-kV SiC MOSFETs and well below the SiC 1-D unipolar limit. To date, this is the first report of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$3\text{-kV}+$</tex> E-mode GaN devices, and our MC <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> -HEMTs show the highest Baliga's figure-of-merits in all <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$6.5\text{-kV}+$</tex> transistors. The MC <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> -HEMT is also applicable to other materials, e.g., (Al)GaO and Al(Ga)N, as a platform design for multi-channel power transistors.