Electrical and reliability characteristics of GaAs MOSHEMTs utilizing high-k IIIB and IVB oxide layers

In this work, the high-k material of gadolinium oxide layer (Gd2O3) and zirconium oxide layer (ZrO2) thin films were fabricated as the gate dielectric insulator materials in GaAs metal–oxide–semiconductor high electron mobility transistors (MOSHEMTs). The dielectric constant of Gd2O3 and ZrO2 oxide layers were estimated to be 10.6 and 7.3 by the MOS-ring capacitor of C–V measurements. In addition, the thermal stability of the devices have been investigated and compared with the high-k material Gd2O3 and ZrO2 thin films for reliability tests. The Gd2O3 MOSHEMTs achieved a better thermally stable characteristic duo to its similar lattice structure with GaAs native oxide layer. At high temperature operation, the VBR degradation slope was 1.2 × 10−3 V/°C and the maximum Ids degradation slope was 1.4 × 10−2 mA (%)/°C. According to this, the device also showed a good reliability characteristic within 48 h. Based on measurement results, the Gd2O3 MOSHEMTs exhibited the best electrical characteristics, including the lowest gate leakage current, the lowest noise spectra density, and the high power performance. Therefore, the Gd2O3 MOSHEMTs is suitable for high power amplifier and monolithic microwave integrated circuits (MMICs) applications.