Two-dimensional buffer breaks substrate limit in III-nitrides epitaxy

Expanding the diversity of substrate materials for the growth of single-crystalline films enables the heterointegration of electronic and optoelectronic devices in modern semiconductor industry. However, the substrate materials are restricted to those having matched single-crystalline lattices with the epilayers, thereby making the use of non-single-crystalline substrates infeasible. Here, we report an epitaxy strategy for the wafer-scale growth of high-quality single-crystalline gallium nitride (GaN) on an amorphous silicon dioxide (SiO₂) substrate. We achieve this result through a chemical bond transition, converting multilayer molybdenum disulfide (MoS₂) to molybdenum nitride (MoN), which serves as a buffer layer to engineer a preferred orientation for the epitaxy of the overlying GaN film. Using this method, we also demonstrate the growth of an AlGaN/AlN/GaN heterostructure with high electron mobility exceeding 2000 square centimeters per volt per second. The resultant high-electron-mobility transistors exhibit subthreshold swing, on/off ratio, and threshold voltage comparable to those commercial devices.