Tungsten-Gated GaN/AlGaN p-FET With Imax > 120 mA/mm on GaN-on-Si

This letter demonstrates Tungsten (W) -gated p -channel GaN/AlGaN heterostructure field effect transistors on a GaN-on-Si wafer grown by metal organic chemical vapor deposition (MOCVD). The choice of W as the gate metal over the more commonly used Mo induces larger turn-on voltage and lower gate leakage current. An annealing step at 500 °C in N 2 ambient was introduced to heal the damage introduced during the gate recess step which resulted in lower channel resistance. Long-channel W-gated p -FETs with L {ₒ₃}=5. 5\, \, m and L {₆}=1. 5\, \, m exhibits an I {₎₍} 25 mA/mm, I {₎₍}/I {₎₅₅}>10^3. A scaled transistor of dimensions L {ₒ₃}=1. 2\, \, m and L {₆}=100 nm demonstrates an I {₎₍} 125 mA/mm, I {₎₍}/I {₎₅₅} 10^4, and R {₎₍}=170\, \, {mm}.