Investigation into the impact of source-drain series resistance on electrical parameters of AlGaN/GaN high electron mobility transistors

Abstract

This research investigates the impact of source-drain series resistance (R_SD) AlGaN/GaN high-electron-mobility transistors (HEMTs). Initially, the influence of R_SD was analyzed in devices with varying geometries (Length and width; L_g and W) as well as in devices with identical dimensions but fabricated using different gate metal manufacturing techniques. Subsequently, the effect of R_SD on key parameters, including carrier mobility (μ_n), effective mobility (${\mu }_{\mathrm{eff}}$) and field effect mobility (${\mu }_{\mathrm{FE}}$), drain current ($I_d$), output conductance ($g_d$), transconductance ($g_m$), threshold voltage ($V_T$) and subthreshold slope ($S$) was assessed. The results reveal that R_SD tends to decrease in transistors with lower L_g and higher W, highlighting a significant correlation with the channel’s geometric structure. Additionally, transistors employing different gate metal splits exhibited variations in R_SD. The results further revealed that a lower R_SD enhances μ_n, ${\mu }_{\mathrm{eff}}$, ${\mu }_{\mathrm{FE}}$, $I_d$, $g_d$, $g_m$, and $S,$ while reducing $V_T$.