Unifying epitaxial growth and microfabrication processes for GaN semiconductor material and devices

The foundation of compound semiconductor technology is in epitaxial growth processes, such as molecular beam epitaxy and metalorganic chemical vapor deposition. In these techniques, controlled deposition of thin films suitable for electronic and optoelectronic devices are typically performed in planar geometries, where the atomic arrangement of growing layers are dictated by the existing template. This has been the basis for production of III-V semiconductor device material of suitable crystalline perfection to be used in high efficiency solar cells, high-speed and high-power transistors, and light-emitting diodes. In this talk, a different paradigm of crystal growth is explored, involving the integral use of microfabrication processes. Here, the MOCVD growth of GaN is extended by the use of selective area growth, where the area of crystal growth can be pre-defined by the modification of the planar surface used as a template. This is shown by the preparation of single-crystalline GaN layers on an amorphous surface by the use of a vertically and laterally confined dielectric ‘tunnel mask’.