A pseudomorphic high electron mobility transistor (PHEMT) power device formed on a double planar doped epitaxial substrate and capable of operating with a single voltage source and a method for manufacturing the PHEMT power device are provided. The PHEMT power device includes: an epitaxial substrate including a GaAs buffer layer, an AlGaAs/GaAs superlattice layer, an updoped AlGaAs layer, a first doped silicon layer, a first spacer, an InGaAs electron transit layer, a second spacer, a second doped silicon layer having a different doping concentration from the first doped silicon layer, a lightly doped AlGaAs layer, and an undoped GaAs cap layer stacked sequentially on a semi-insulating GaAs substrate; a source electrode and a drain electrode formed on and in ohmic contact with the undoped GaAs cap layer; and a gate electrode formed on the lightly doped AlGaAs layer to extend through the undoped GaAs cap layer.