Characteristics of AlGaN/GaN heterostructure field effect transistor grown on 4 inch Si (111) substrate using formation of dot-like AlSi<inf>x</inf>C<inf>1−x</inf> interlayer

Abstract

Group III-nitride semiconductors and their ternary solid solutions are very promising as the candidates for both short wavelength optoelectronics and power electronic devices [1]. The AlGaN/GaN heterostructure field-effect transistors (HFETs) have a great potential for future high-frequency and high-power applications because of the intrinsic advantages of materials such as wide band gap, high breakdown voltage, and high electron peak velocity [2–4]. Si substrate is considered as a promising candidate to replace expensive and small wafers such as sapphire and SiC, even though the GaN layer grown on Si substrate has a large strain and dislocation due to a large lattice mismatch and thermal expansion coefficient difference between the grown GaN layer and the Si substrate. The mismatch between thermal expansion coefficients is about 56%, which induces a large tensile stress and may cause a severe crack generation in the grown GaN films during the cooling process after growth. In this work, for the purpose of reducing the crack density in the AlGaN/GaN heterostructure grown on Si substrate, we have grown dot-like AlSi <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</inf> C <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1−x</inf> interlayer in inital growth state between AlN and Si substrate and demonstrated successful normally-on/off GaN HFET grown on silicon substrate.