High RF Performance AlGaN/GaN HEMTs on 6-in Si Substrate for Low Voltage Applications

In this letter, AlGaN/GaN high electron mobility transistors (HEMTs) on a 6-inch Si substrate with excellent RF performance are presented for low voltage applications. Using regrown n+-InGaN ohmic contacts by metal-organic chemical vapor deposition, the ohmic contact resistance achieves an average value of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.08~\Omega \cdot $ </tex-math></inline-formula>mm on the whole wafer. With a gate length of 220 nm and a source-drain spacing of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$2.2~\mu $ </tex-math></inline-formula>m, the device exhibits a saturation current of up to 1689 mA/mm and a peak transconductance of 436 mS/mm. Once the wafer was thinned to <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$100~\mu $ </tex-math></inline-formula>m, 3.6 GHz load-pull measurements for the HEMT with gate width (<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${W}_{\text {g}}\text {)}$ </tex-math></inline-formula> of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$2\times 100~\mu $ </tex-math></inline-formula>m at low drain voltages (<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${V}_{\text {d}}\text {)}$ </tex-math></inline-formula> of 5-15 V indicate that the device exhibits maximum output power densities (<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${P}_{ {\text {out}, {max}}} )$ </tex-math></inline-formula> of 0.86-4.35 W/mm and peak power added efficiencies (PAE) of 63.96%-66.23%, which are the highest output power density and PAE from AlGaN/GaN HEMTs at the same operating voltage level in sub-6GHz. Furthermore, the HEMT with <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${W}_{\text {g}}$ </tex-math></inline-formula> of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$8\times 125~\mu $ </tex-math></inline-formula>m also shows high PAE of 60.4%/61.19% and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${P}_{ {\text {out}, {max}}}$ </tex-math></inline-formula> of 0.56/0.75 W/mm at <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${V}_{\text {d}} =5$ </tex-math></inline-formula>/6 V. The excellent properties of these AlGaN/GaN HEMTs on Si illustrate their suitability for addressing specific RF application scenarios, including portable communication devices, wireless sensor networks and so on.