Self-planarized quantum-disks-in-nanowires ultraviolet-B emitters utilizing pendeo-epitaxy

Area of Science:

• Materials Science
• Optoelectronics
• Semiconductor Physics

Background:

• Achieving uniform, vertically aligned nanowires (NWs) is crucial for efficient light-emitting devices but remains a significant challenge.
• Self-assembled growth of Aluminum Gallium Nitride (AlGaN) nanowires often suffers from defects, impacting device performance.

Purpose of the Study:

• To demonstrate a method for growing dislocation-free AlGaN nanowires with spontaneous coalescence for optoelectronic applications.
• To fabricate efficient ultraviolet-B (UV-B) light-emitting diodes (LEDs) on silicon substrates.

Main Methods:

• Plasma-assisted molecular beam epitaxy (MBE) was used to grow AlGaN nanowires on n-type doped silicon (100) substrates.
• Optimized growth conditions achieved a high nanowire density (>95% filling factor), eliminating the need for planarization.
• Fabrication involved a large active region with 15 stacks of AlxGa1-xN/AlyGa1-yN quantum-disks and a graded layer for improved carrier injection.

Main Results:

• Dislocation-free AlGaN nanowires with spontaneous coalescence were successfully grown.
• UV-B LEDs emitting at ~303 nm with a narrow spectral width (FWHM ~20 nm) were demonstrated.
• The developed method allows for the fabrication of ultra-thin optoelectronic devices on scalable silicon substrates.

Conclusions:

• This study presents a viable approach for fabricating efficient, ultra-thin UV optoelectronic devices on low-cost silicon.
• The use of coalesced, dislocation-free AlGaN nanowires facilitates device fabrication and enhances performance.
• The demonstrated technology holds promise for scalable production of UV-B LEDs.