Instability investigation of In0.7Ga0.3As quantum-well MOSFETs with Al2O3 and Al2O3/HfO2

• We performed the instability investigation on InGaAs quantum-well InGaAs MOSFETs.
• The InGaAs MOSFET with Al2O3/HfO2 exhibits better electrostatic integrity, however, it shows worse reliability and frequency dispersion behavior than one with Al2O3.
• At cryogenic temperature, the device with Al2O3/HfO2 induces worse hysteresis behavior than one with Al2O3.

We present an instability investigation of In0.7Ga0.3As quantum-well (QW) metal–oxide–semiconductor field-effect-transistors (MOSFETs) on InP substrate with Al2O3 and Al2O3/HfO2 gate stacks. The device with bi-layer Al2O3/HfO2 gate stack exhibits larger shift in threshold-voltage (ΔVT) under a constant-voltage-stress condition (CVS), than one with single Al2O3 gate stack. At cryogenic temperature, the device with bi-layer Al2O3/HfO2 gate stack also induces worse hysteresis behavior than one with single Al2O3 gate stack. These are mainly attributed to more traps inside the HfO2 material, yielding a charge build-up inside the HfO2 gate dielectric. This strongly calls for a follow-up process to minimize those traps within the high-k dielectric layer and eventually to improve the reliability of InGaAs MOSFETs with HfO2-based high-k gate dielectric.