Thermal Stability Study of GaP/High‐k Dielectrics Interfaces

High-quality interface between high-mobility III–V compound semiconductor and high-k dielectrics is critical for achieving high electrical performance of the devices. Elemental diffusion through the high-k dielectrics from III–V semiconductors (e.g., InP, InAs, and InGaAs) upon the atomic layer deposition process and during the postdeposition annealing (PDA) at low temperature rises a concern with the reliability of III–V compound semiconductor devices. In this work, the thermal stability of GaP/high-k dielectrics interface has been studied in terms of elemental diffusion upon PDA, using angle-resolved X-ray photoelectron spectroscopy. The Ga and P oxides are below the detection limit of X-ray photoelectron spectroscopy for the GaP/HfO2 stack after PDA at 400 °C, and for the GaP/Al2O3 stack after PDA at 500 °C. Outdiffusion of Ga and P atoms through HfO2 film is detected by time-of-flight secondary ions mass spectrometry after PDA at 500 and 600 °C. Highly stable GaP/high-k dielectrics interfaces suggest that a thin barrier layer of wide bandgap GaP between the III–V semiconductor channel materials and high-k dielectrics would benefit the reliability of the devices.