Investigation of enhancement-mode metamorphic InAlAs/InGaAs HEMTs by Schottky metal diffusion

In this report, we have developed the enhancement mode (E-mode) InAlAs/InGaAs metamorphic HEMT´s (mHEMTs) on GaAs substrates by using the thermally annealed Schottky metal diffusion approach. The activation energy of platinum (Pt) Schottky metal was systematically carried out. Based on the extracted device small-signal model, the improved devices rf transconductance (g_m) is more significantly than the increased gate-to-source capacitance (C_gs) after the Schottky metal diffusion, due to the reduction of gate-to-channel separation. Moreover, it also exhibits a high voltage gain and capacitance ratio resulting in a higher maximum oscillation frequency.