US Patent 11923454 Epitaxial structure having super-lattice laminates

An epitaxial structure includes a substrate, a lower super-lattice laminate, a middle super-lattice laminate, an upper super-lattice laminate and a channel layer. The lower super-lattice laminate includes a plurality of first lower film layers and a plurality of second lower film layers stacked alternately. The first lower film layer includes aluminum nitride. The second lower film layer includes aluminum gallium nitride. The middle super-lattice laminate includes a plurality of first middle film layers and a plurality of second middle film layers stacked alternately. The first middle film layer includes aluminum nitride. The second middle film layer includes gallium nitride doped with a doping material. The upper super-lattice laminate includes a plurality of first upper film layers and a plurality of second upper film layers stacked alternately. The first upper film layer includes gallium nitride doped with the doping material. The second upper film layer includes gallium nitride.