The invention relates to an epitaxial structure for
nitride high electron mobility transistors of composite buffer
layers, which includes that a growth nucleating layer is arranged on a substrate; a first buffer layer is arranged on the growth nucleating layer; a second buffer layer is arranged on the first buffer layer; a growth channel layer is arranged on the second buffer layer; and a growth
barrier layer is arranged on the growth channel layer. The growth method includes baking the substrate at a high temperature in a
reaction chamber after the substrate is washed and dried; growing the nucleating layer on the substrate, the first buffer layer on the nucleating layer, the second buffer layer on the first buffer layer, the growth channel layer on the second buffer layer, and the growth
barrier layer on the channel layer; and reducing the temperature to the
room temperature. The epitaxial structure for
nitride high electron mobility transistors of composite buffer
layers has the advantages of being still capable of forming
conduction band discontinuity with a
gallium nitride (GaN) channel layer, enhancing 2 dimensional
electron gas (DEG) confinement, improving
microwave performances and power characteristics of devices, being capable of improving the heat
conductivity of the buffer layer, and effectively reducing self-
heating effect of
high electron mobility transistors (HEMT) of AlGaN buffer layer. Quality of crystals of AlyGal-yN buffer layer can be effectively improved, and the epitaxial structure is helpful for further improving the performance and reliability of devices.