Measuring the roughness of buried interfaces by sputter depth profiling.

Area of Science:

• Materials Science
• Nanotechnology
• Surface Science

Background:

• Atomic Layer Deposition (ALD) enables precise nanoscale material growth.
• Understanding interfacial properties is crucial for optimizing nanostructure performance.
• MgO/ZnO multilayers are promising for various electronic and optical applications.

Purpose of the Study:

• To characterize the interfacial roughness of MgO/ZnO nanolayers grown by ALD.
• To determine the origin of interfacial roughness (native vs. interdiffusion).

Main Methods:

• High-resolution sputter depth profiling using dual beam time-of-flight secondary ion mass spectrometry (ToF-SIMS).
• Analysis of depth profiles using the mixing-roughness-information (MRI) model.
• Cross-validation with specular x-ray reflectivity (XRR).

Main Results:

• ALD grown MgO/ZnO nanolayers exhibit a nanolayer interfacial roughness of approximately 1.5 nm.
• Specular XRR analysis confirmed the MRI model's findings.
• The observed roughness is consistent with native/jig-sawed interfaces.

Conclusions:

• The interfacial roughness in ALD-grown MgO/ZnO multilayers is primarily due to native interface formation.
• Interfacial interdiffusion is not the dominant factor contributing to roughness during ALD growth of these materials.
• Precise control over interfacial structure is achievable with ALD, with roughness being an intrinsic characteristic of the interface formation process.