Correlated Surface Morphology and Sc Content Tuning in ScGaN Epilayers by Molecular Beam Epitaxy for Photonic Devices

Scandium (Sc)-III-nitrides, new members of the III-nitride family, are well-known for their ferroelectric properties. Their other unique material properties have further extended their applications beyond ferroelectric devices to light-emitting diodes (LEDs), optoelectronic devices, and photocatalysis. Tuning the morphology of Sc-III-nitrides is essential for these applications. This study provides insights into tuning the surface morphology as well as the Sc content of ScGaN epilayers grown by molecular beam epitaxy (MBE) under N-rich conditions. It is found that the surface features are dependent not only on the Ga/Sc ratio but also on the nitrogen flow rate. It is also found that the Sc content depends on both the Ga:Sc ratio and the incident Ga flux. Detailed characterization using atomic force and electron microscopies further unveils the possible underlying mechanism of the observed porous surface.