Bendable Microwave AlGaN/GaN High-Electron-Mobility Transistor With Output Power Density of 2.65 W/mm

Abstract

Flexible radio frequency (RF) devices are in high demand for wearable electronics; however, they currently do not offer sufficient output power for application in fifth-generation wireless communication systems. This paper reports a bendable gallium nitride (GaN) high-electron-mobility-transistor (HEMT) with state-of-the-art output power in the microwave band. In this study, a fabrication method is proposed, where HEMT is originally grown on silicon carbide (SiC) substrates. After thinning the SiC substrates 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">$5~\mu \text{m}$ </tex-math></inline-formula> , HEMT is transferred using a copper film rather than flexible substrates used in other studies. The measurements indicated that the fabricated devices exhibited a saturation output power of 2.65 W, corresponding to a power density of 2.65 W/mm, which was associated with maximum power added efficiency (PAE) of 51% at 3 GHz. The performance of the fabricated device remained stable even with a bending radius of up to 0.6 cm. These results indicated that the proposed fabrication method can potentially be used to realize high-power flexible RF electronics.