Conductive metal oxide based gates for self-aligned technology of AlGaN/GaN HEMTs

We present advanced gate interface of AlGaN/GaN HEMTs for self-aligned gate processing technology. The in-diffusion of the gate metal components to the AlGaN barrier layer can be eliminated. It can be done by inserting thin conductive metal oxide layer on the interface between the metal and the wide bandgap semiconductor layer. The proposed gate electrodes are prepared by thermal oxidation of high work function metals as Ni or Ir (RTA in pure O₂ ambient at T=800 °C for 1 min). The highest value of oxidation temperature is limited by the optimal temperature of the ohmic contact formation. It is shown that high temperature formation of IrO₂ and NiO gate contact layers has no significant impact on transport parameters of 2DEG channel of AlGaN/GaN HEMT structures thus it could be applied in self-aligned gate processing technology of the device.