Distinguishing cubic and hexagonal phases within InGaN/GaN microstructures using electron energy loss spectroscopy

Area of Science:

• Materials Science
• Solid State Physics
• Nanotechnology

Background:

• 3D Indium Gallium Nitride/Gallium Nitride (InGaN/GaN) microstructures are vital for optoelectronic devices.
• Metal Organic Vapor Phase Epitaxy (MOVPE) and Molecular Beam Epitaxy (MBE) are key growth techniques.
• Crystal phase variations, particularly cubic inclusions in hexagonal wurtzite GaN, impact device performance.

Purpose of the Study:

• To investigate the crystal phase differences in 3D InGaN/GaN microstructures.
• To develop a method for mapping cubic and hexagonal GaN regions.
• To understand how crystal phase affects electronic properties of light-emitting devices.

Main Methods:

• Utilized a range of electron microscopy techniques.
• Employed Electron Energy Loss Spectroscopy (EELS) to analyze material.
• Focused on variations in the fine structure of the Nitrogen K-edge (N K-edge).

Main Results:

• Observed clear differences in the N K-edge fine structure between cubic and hexagonal GaN.
• Successfully mapped cubic and hexagonal regions within a GaN/InGaN microcolumnar device.
• Demonstrated the capability of EELS for phase differentiation.

Conclusions:

• EELS is an effective technique for distinguishing and mapping cubic and hexagonal GaN phases.
• Understanding and mapping these phases is essential for optimizing InGaN/GaN devices.
• Spatial resolution limitations of the mapping method were discussed.