Progress in wide bandgap technology

AbstractThe developing list of wide gap substrates for device production is remarkable compared with a few years ago and continues to provide new device design possibilities. For GaN it ranges from the largest volume (and hetero) materials, sapphire and SiC (both available in 2″–4″ diameters and used for commercial devices) to homo and hetero substrates that now include four compound materials; aluminium nitride (AIN), gallium nitride (GaN), silicon carbide (SiC), and zinc oxide (ZnO). These are all available commercially, but in varying stages of size, unit volumes, surface and defect qualities. Additionally, a fifth substrate has been announced in the form of HVPE-grown aluminium gallium nitride (AlGaN) available in development quantities. Their production processes include several types of vapiur phase epitaxy, vapour phase transport, crystallisation from the melt and solution growth. Since they are all wide gap materials, these production methods are all high temperature processes and some require high pressures