Low-temperaturevan der waals epitaxy of GaN films on graphene through AlN buffer by plasma-assisted molecular beam epitaxy

Abstract

Low-temperature growth of III-nitride semiconductor materials on non-single-crystalline substrates is necessary to realize inexpensive and large-area transferable GaN-films for flexible devices. In this work, the growth conditions and material properties of III-nitride films have been explored using plasma-assisted molecular beam epitaxy and AlN as a buffer layer. Migration enhanced epitaxy mode is the most suitable for the realization of low-temperature van der Waals epitaxy (vdWE). An AlN buffer layer with thickness of 10 nm grown by the MEE mode results in the optimizedcrystalline quality and surface flatness, which is extremely beneficial for the subsequentGaN film epitaxy. A single-crystalline GaN film with a flat surface has been obtained on AlN/graphene/quartz substrate at 530 °C, possessinga dislocation density about 1.10 × 1011 cm−2 and a RMS surface roughness of 2.04 nm for 10 × 10 μm2 area. The results obtained in this work can be applied to vdWE of III-nitrides on other 2D material/non-single-crystalline substrates for their further applications in flexible devices or circuits.