2DEG-Concentration-Modulated High-Power-Density AlGaN/GaN RF HEMTs

Herein, by modulating 2DEG concentration (<inline-formula> <tex-math notation="LaTeX">${n} _{\mathbf {s}}$ </tex-math></inline-formula>), a superior GaN RF HEMT with a high-Al-content AlGaN barrier is reported for high power-density (<inline-formula> <tex-math notation="LaTeX">${P} _{\text {out}}$ </tex-math></inline-formula>) X-band applications. Thanks to a high <inline-formula> <tex-math notation="LaTeX">${n} _{\text {s}}$ </tex-math></inline-formula> of <inline-formula> <tex-math notation="LaTeX">${1}.{3}\times {10} ^{{13}}$ </tex-math></inline-formula> cm<inline-formula> <tex-math notation="LaTeX">$^{-{2}}$ </tex-math></inline-formula> enabled by the Al<inline-formula> <tex-math notation="LaTeX">$_{{0}.{32}}$ </tex-math></inline-formula> Ga<inline-formula> <tex-math notation="LaTeX">$_{{0}.{68}}$ </tex-math></inline-formula> N barrier, as well as the regrown n+ -GaN ohmic contacts, the device exhibits an output drain current (<inline-formula> <tex-math notation="LaTeX">${I} _{\text {D}}$ </tex-math></inline-formula>) of 1.6 A/mm, an on-resistance (<inline-formula> <tex-math notation="LaTeX">${R} _{\text {ON}}$ </tex-math></inline-formula>) of <inline-formula> <tex-math notation="LaTeX">$1.10\Omega ~\cdot $ </tex-math></inline-formula>mm, and maintain a breakdown electric field (<inline-formula> <tex-math notation="LaTeX">${E} _{\text {BC}}$ </tex-math></inline-formula>) of ~0.8 MV/cm. As a result, at 10 GHz, <inline-formula> <tex-math notation="LaTeX">${P} _{\text {out}}$ </tex-math></inline-formula> of 10.4 W/mm and power-added efficiency (PAE) of 63.2% are obtained at a moderate drain bias (<inline-formula> <tex-math notation="LaTeX">${V} _{\text {D}}$ </tex-math></inline-formula>) of 28 V. Notably, the results of <inline-formula> <tex-math notation="LaTeX">${I} _{\mathbf {D}}$ </tex-math></inline-formula> – <inline-formula> <tex-math notation="LaTeX">${E} _{\text {BC}}$ </tex-math></inline-formula>, <inline-formula> <tex-math notation="LaTeX">${P} _{\text {out}}$ </tex-math></inline-formula> – <inline-formula> <tex-math notation="LaTeX">${V} _{\text {D}}$ </tex-math></inline-formula>, and the figure-of-merit <inline-formula> <tex-math notation="LaTeX">${P} _{\text {out}}$ </tex-math></inline-formula> / <inline-formula> <tex-math notation="LaTeX">${V} _{D}$ </tex-math></inline-formula> of our device marks one of the best records among X-band GaN HEMTs, showing strong competitiveness of high-Al-content AlGaN/GaN HEMTs for high-<inline-formula> <tex-math notation="LaTeX">${P} _{\text {out}}$ </tex-math></inline-formula> RF applications.