Flexible Gallium Nitride for High-Performance, Strainable Radio-Frequency Devices

Abstract

Flexible gallium nitride (GaN) thin films can enable future strainable and conformal devices for transmission of radio-frequency (RF) signals over large distances for more efficient wireless communication. For the first time, strainable high-frequency RF GaN devices are demonstrated, whose exceptional performance is enabled by epitaxial growth on 2D boron nitride for chemical-free transfer to a soft, flexible substrate. The AlGaN/GaN heterostructures transferred to flexible substrates are uniaxially strained up to 0.85% and reveal near state-of-the-art values for electrical performance, with electron mobility exceeding 2000 cm² V⁻¹ s⁻¹ and sheet carrier density above 1.07 × 10¹³ cm⁻². The influence of strain on the RF performance of flexible GaN high-electron-mobility transistor (HEMT) devices is evaluated, demonstrating cutoff frequencies and maximum oscillation frequencies greater than 42 and 74 GHz, respectively, at up to 0.43% strain, representing a significant advancement toward conformal, highly integrated electronic materials for RF applications.

Flexible gallium nitride (GaN) thin films and devices are described that enable amplification of radio-frequency signals in future conformal and wearable electronics. Flexible GaN is realized through lift-off using a 2D boron nitride release layer and can accommodate strains up to 0.43%, while exhibiting electron mobility and small signal frequency performance rivaling high-performing, rigid GaN materials.

http://ift.tt/2lGQmqj