Comparative study of InGaP/GaAs high electron mobility transistors with upper and lower $\delta$-doped supplied layers

Influence corresponding to the position of $\delta$-doped supplied layer on InGaP/GaAs high electron mobility transistors is comparatively studied by two-dimensional simulation analysis. The simulated results exhibit that the device with lower $\delta$-doped supplied layer shows a higher gate potential barrier height, a higher saturation output current, a larger magnitude of negative threshold voltage, and broader gate voltage swing, as compared to the device with upper $\delta$-doped supplied layer. Nevertheless, it has smaller transconductance and inferior high-frequency characteristics in the device with lower $\delta$-doped supplied layer. Furthermore, a knee effect in current-voltage curves is observed at low drain–to–source voltage in the two devices, which is investigated in this article.