Site controlled red-yellow-green light emitting InGaN quantum discs on nano-tipped GaN rods

Area of Science:

• Semiconductor Physics
• Materials Science
• Optoelectronics

Background:

• Indium Gallium Nitride (InGaN) based materials are crucial for visible light emission.
• Defects like dislocations and coalescence in InGaN structures often lead to emission problems.
• Existing methods for InGaN growth can be complex, requiring strain relaxation and alloy compositional changes.

Purpose of the Study:

• To develop a method for growing site-controlled InGaN multiple quantum discs (QDs) with uniform wafer scale.
• To eliminate emission issues in InGaN visible light sources by utilizing coalescence-free nanorod templates.
• To demonstrate control over emission color (red, yellow, green) by manipulating QD dimensions.

Main Methods:

• Utilized metal organic chemical vapour deposition (MOCVD) for growth.
• Employed ultra-high density (>80%) coalescence-free nanorod templates.
• Applied correlative scanning transmission electron microscopy (STEM), energy-dispersive X-ray (EDX) mapping, and cathodoluminescence (CL) hyperspectral imaging.

Main Results:

• Achieved site-controlled InGaN QDs at uniform wafer scale on nanorod templates.
• Eliminated dislocations and coalescence, resolving common emission problems.
• Demonstrated controlled site selection of red, yellow, and green (RYG) emission via nano tips.
• Showed that RYG emission is achieved by manipulating InGaN QD confinement dimensions, not solely by increasing Indium percentage.

Conclusions:

• The MOCVD method on nanorod templates offers a defect-free approach for InGaN quantum discs.
• Emission color tuning is effectively managed by controlling QD dimensions, simplifying growth processes.
• This technique enables high-quality InGaN growth without complex strain relaxation or alloy compositional adjustments.