Enhanced Breakdown Voltage With High Johnson's Figure-of-Merit in 0.3-um T-gate AlGaN/GaN HEMTs on Silicon by (NH_4)_2S_x Treatment

摘要

Enhanced OFF -state breakdown voltage has been observed in ammonium sulfide $[({rm NH}_{4})_{2}{rm S}_{x}]$-treated AlGaN/GaN high electron mobility transistors (HEMTs) on Si substrate without compromising the unit gain cutoff frequencies. About six times higher OFF -state breakdown voltage $({rm BV}_{rm gd})$ and three orders of magnitude higher $I_{rm ON}/I_{rm OFF}$ ratio were observed in the $({rm NH}_{4})_{2}{rm S}_{x}$-treated 0.3-$mu{rm m}$ T-gate conventional AlGaN/GaN HEMTs on Si substrate. In addition, three orders of magnitude lower surface leakage current (${sim}{rm 3.0}~mu{rm A/mm}$ to ${sim}{rm 3}~{rm nA/mm}$) have also been observed on the $({rm NH}_{4})_{2}{rm S}_{x}$ -treated devices. The calculated Johnson's figures of merit $({rm Jhbox{-}FOM}={rm BV}_{rm gd}times f_{rm T})$ is $5.41times 10^{12}~{rm V/s}$, which is the highest value reported so far for 0.3- $mu{rm m}$ T-gate conventional SiN passivated AlGaN/GaN HEMTs without the incorporation of field plate. No significant drain current collapse was observed on the $({rm NH}_{4})_{2}{rm S}_{x}$-treated devices.