InP PHEMT epitaxial structure and preparation method thereof

The invention discloses an InP PHEMT epitaxial structure and a preparation method thereof, the epitaxial structure comprises an InP substrate, a gradient buffer layer, a channel layer, an isolation layer, a Si plane doping layer, a barrier layer, an etching stop layer, a first contact layer and a second contact layer which are sequentially stacked from bottom to top, the gradient buffer layer is made of InAAs, x is sequentially and continuously increased from 0.52 to 0.8 from the lower end to the upper end of the gradient buffer layer, the communication layer is made of InyGa1-yAs, and y is larger than or equal to 0.8 and smaller than or equal to 1. Due to the fact that the In component in the graded buffer layer is continuously graded, the lattice constant of the virtual substrate is increased, the lattice constant is slowly increased, growth of a channel layer with high quality and high In component is facilitated, and the electron mobility of two-dimensional electron gas of the InP PHEMT epitaxial st