Al₂O₃ Passivation Effect in HfO₂·Al₂O₃ Laminate Structures Grown on InP Substrates

Area of Science:

• Materials Science
• Semiconductor Physics
• Surface Chemistry

Background:

• Indium phosphide (InP) is a critical semiconductor material.
• High-k dielectrics like Hafnium oxide (HfO2) are essential for advanced electronics.
• Interfacial reactions in HfO2/InP systems degrade electrical properties.

Purpose of the Study:

• To investigate the passivation effect of an Aluminum oxide (Al2O3) layer on HfO2-Al2O3 laminate structures.
• To understand the role of Al2O3 layer sequence in mitigating interfacial reactions.
• To optimize the electrical characteristics of HfO2-based dielectrics on InP.

Main Methods:

• Atomic-layer deposition (ALD) for growing HfO2-Al2O3 laminate structures on InP.
• High-resolution X-ray photoelectron spectroscopy (XPS) for chemical state analysis.
• Electrical characterization, including conductance measurements.

Main Results:

• The Al2O3/HfO2/Al2O3 structure exhibited superior electrical properties compared to HfO2/InP.
• The top Al2O3 layer prevented oxidant diffusion, while the bottom Al2O3 layer blocked In/P outdiffusion.
• Formation of In-O bonds was suppressed, and midgap traps were reduced to 2.6 × 10^12 eV^-1 cm^-2.

Conclusions:

• Al2O3 passivation effectively suppresses interfacial reactions and defects in HfO2/InP systems.
• The Al2O3/HfO2/Al2O3 stack is a promising dielectric for InP-based devices.
• Minimizing gap states is crucial for preventing leakage current and improving capacitor reliability.