Thickness Effect on the Solid-State Reaction of a Ni/GaAs System.

Area of Science:

• Materials Science
• Solid-State Chemistry
• Thin Film Technology

Background:

• Understanding solid-state reactions between thin metal films and semiconductor substrates is crucial for microelectronic device fabrication.
• Nickel (Ni) and gallium arsenide (GaAs) interactions are fundamental for forming intermetallic compounds with potential applications.

Purpose of the Study:

• To investigate the influence of Ni thin film thickness on the solid-state reaction and intermetallic phase formation with a GaAs substrate.
• To determine the thickness dependence of epitaxial relationships, phase formation temperatures, and decomposition behaviors.

Main Methods:

• Magnetron sputtering for Ni thin film deposition on GaAs.
• In situ and ex situ X-ray diffraction (XRD) for phase identification and texture analysis.
• Atom probe tomography (APT) for detailed interfacial and compositional analysis.

Main Results:

• Epitaxial growth of Ni on GaAs observed for 20 nm films, with specific crystallographic orientations.
• Increasing Ni film thickness altered the Ni film's texture, impacting the formation temperature of Ni3GaAs.
• Ni3GaAs phase decomposed into NiAs and Ni3-xGaxAs1-x compounds around 400 °C, with decomposition temperature dependent on initial Ni thickness.

Conclusions:

• Ni film thickness is a critical parameter controlling the solid-state reaction kinetics and phase formation at the Ni/GaAs interface.
• The nature of the Ni/GaAs interface (coherent vs. incoherent) significantly influences the observed reaction pathways and temperatures.
• The findings provide insights into controlling intermetallic compound formation for potential electronic applications.