Free-standing Lateral AlGaN/GaN Schottky Barrier Diode Based-on GaN-on-Si Technology for High Microwave Power Applications

This paper presents the development of a lateral AlGaN/GaN Schottky barrier diode (SBD) on free-standing GaN epilayers achieved through Si substrate removal for GaN-on-Si technology. Compared to conventional SBDs on GaN-on-Si, the newly developed free-standing AlGaN/GaN SBDs exhibit enhanced RF performance (cut-off frequency (f<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">C</inf>) and ideality factor (η<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">n</inf>) without compromising DC performance. DC results reveal an onset voltage (V<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ON</inf>) of 1.34 V, on-resistance (R<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ON</inf>) of 1.6 Ω•mm, and η<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">n</inf> of 1.7 (14% improvement). Reverse-breakdown voltage (V<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">BV</inf>) exceeds 30 V, with a reverse-bias leakage current (I<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">R</inf>) below 38 μA/mm. RF performance demonstrates a f<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">C</inf> of 80.2 GHz at zero-bias (11.14% enhancement). The impact of lossy Si substrate coupling effects on RF performance for both SBD structures was studied using 3D-EM simulations for further performance optimisation. These findings imply integrated GaNbased SBDs on Si technology are suitable for high-power and high-temperature system applications at millimetre-wave frequencies, particularly in conjunction with high-thermal coefficient materials such as diamond and AlN.