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

Abstract

In this work, the high-k material of gadolinium oxide layer (Gd 2O 3) and zirconium oxide layer (ZrO 2) thin films were fabricated as the gate dielectric insulator materials in GaAs metal–oxide–semiconductor high electron mobility transistors (MOSHEMTs). The dielectric constant of Gd 2O 3 and ZrO 2 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 Gd 2O 3 and ZrO 2 thin films for reliability tests. The Gd 2O 3 MOSHEMTs achieved a better thermally stable characteristic duo to its similar lattice structure with GaAs native oxide layer. At high temperature operation, the V BR degradation slope was 1.2 × 10 −3 V/°C and the maximum I ds 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 Gd 2O 3 MOSHEMTs exhibited the best electrical characteristics, including the lowest gate leakage current, the lowest noise spectra density, and the high power performance. Therefore, the Gd 2O 3 MOSHEMTs is suitable for high power amplifier and monolithic microwave integrated circuits (MMICs) applications.