First Power Performance Demonstration of Flexible AlGaN/GaN High Electron Mobility Transistor

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

“…[1][2][3] Over the last decade, gallium nitride (GaN) devices have been fundamental and essential elements to meet these requirements for high-power amplification of the radio frequency (RF) signal in MHz to GHz frequencies and beyond, especially for military applications. [16][17][18][19][20][21] Growth of GaN on Si simplifies the substrate etching removal process and has hence been the most widely used approach for development of transferred GaN electronics. [16][17][18][19][20][21] Growth of GaN on Si simplifies the substrate etching removal process and has hence been the most widely used approach for development of transferred GaN electronics.…”

“…[43][44][45] The second indication of the physical impact on the DC performance is the shift in the threshold voltage (V TH ) of −0.03 and −0.17 V under the influence of 0.21% and 0.43% strain, respectively, which is related to the polarization-induced charge density increasing under applied tensile strain. [18] Higher RF performance is presumably achieved as a result of the high-quality epitaxial layer transfer enabled by GaN growth on van der Waals 2D substrates rather than Si. [38] The piezoelectric coefficient of AlGaN is greater than GaN, causing a net increase in the charge carrier density at the interface with tensile strain.…”

“…[4][5][6] As new demands for high-power conformal and flexible electronics for future fifth www.advmat.de www.advancedsciencenews.com lift-off of the GaN film [13][14][15] or etching to chemically remove the substrate. [16][17][18][19][20][21] Growth of GaN on Si simplifies the substrate etching removal process and has hence been the most widely used approach for development of transferred GaN electronics. However, the GaN material grown on Si is typically of lower quality than when grown on sapphire or SiC due to the significant structural and lattice mismatch.…”

“…The reduction here at higher V G is also observed in similar devices transferred to flexible substrates, where as much as a 90% reduction in RF power density as compared to GaN on SiC is observed. [18] For high-power applications flexible/conformal substrates such as metal foils could be used to overcome the self-heating limits imparted by the low thermal conductivity flexible substrates used here.…”

“…This RF performance is superior to previously reported GaN HEMT studies limited to transfer onto a flat, soft substrate, which report an RF figure of merit <4. [18] Higher RF performance is presumably achieved as a result of the high-quality epitaxial layer transfer enabled by GaN growth on van der Waals 2D substrates rather than Si. [46] The extrapolated cutoff frequency is reduced by 9.0% under applied strain due to the linear relationship of cutoff frequency with DC transconductance.…”