High-quality AlN grown with a single substrate temperature below 1200 °C

Area of Science:

• Materials Science
• Semiconductor Growth
• Epitaxy

Background:

• High-quality aluminum nitride (AlN) epitaxy is crucial for optoelectronic and electronic devices.
• Conventional AlN growth often involves complex, time-consuming temperature-varying buffer layers.
• Achieving atomically flat surfaces and low defect densities remains a challenge.

Purpose of the Study:

• To develop a simplified and efficient method for growing device-quality AlN.
• To investigate the impact of pulsed ammonia (NH3) flow on AlN surface morphology and crystal quality.
• To offer an alternative to traditional temperature-varied buffer layer strategies.

Main Methods:

• Aluminum nitride (AlN) layers were grown using metal-organic chemical vapor deposition (MOCVD).
• A single substrate temperature of 1180°C was employed.
• Pulsed ammonia (NH3) flow conditions were utilized, including the insertion of two pulsed-NH3-flow AlN layers.
• X-ray diffraction (XRD) was used to analyze crystal quality.

Main Results:

• Atomically flat AlN surfaces were achieved.
• A narrow X-ray diffraction (XRD) (102) peak width of 427 arcseconds was obtained.
• The pulsed NH3-flow technique effectively released lattice strain through nano-island formation.
• Prolonged lateral migration of aluminum (Al) adatoms contributed to surface smoothening.

Conclusions:

• Pulsed NH3-flow is a viable and simplified alternative to temperature-varied buffer layers for AlN epitaxy.
• This technique significantly improves AlN surface morphology and crystalline quality.
• The simplified growth process facilitates the manufacture of high-quality AlN for device applications.