Topologically Optimized Copper Pre-Orienting Layer Enabled High-Quality GaN Micropyramid Epitaxy on Amorphous Glass

Area of Science:

• Materials Science
• Semiconductor Physics
• Thin Film Technology

Background:

• Heteroepitaxy of single-crystalline gallium nitride (GaN) on glass is desired for low-cost, large-area optoelectronics.
• Amorphous glass lacks the necessary long-range atomic order for crystalline templating.
• Polycrystallization of metal templates on amorphous substrates hinders high-quality epitaxy.

Purpose of the Study:

• To develop a strategy for high-quality GaN epitaxy on amorphous glass substrates.
• To overcome the limitations of amorphous substrates for crystalline material growth.
• To enable low-cost fabrication of GaN-based optoelectronic devices.

Main Methods:

• Introduction of a topologically optimized pre-orienting layer (TOPL) strategy using copper (Cu) (111) thin films.
• Confining grain boundaries within non-epitaxial regions of disconnected Cu thin films during annealing.
• Achieving atomic-level flatness on multiply connected Cu (111) surfaces with sixfold symmetry.

Main Results:

• Successful growth of an aluminum nitride (AlN) buffer layer on the TOPL.
• High-quality c-axis-oriented GaN micropyramid array epitaxy on amorphous glass.
• Glass-based GaN micropyramids exhibit comparable crystalline quality (TDD: 5.46 × 10^8 cm^-2) to sapphire-grown GaN.
• Reduced stress and comparable cathodoluminescence in glass-based GaN.

Conclusions:

• The TOPL strategy effectively enables GaN epitaxy on amorphous glass by overcoming substrate limitations.
• This approach presents a viable pathway for cost-effective, large-area GaN optoelectronics.
• The developed method holds significant promise for future semiconductor device fabrication on unconventional substrates.