Disclosed are a method and a device for manufacturing an array substrate, and an array substrate. The method includes: depositing and forming a gate insulation layer on a pre-formed base substrate and a pre-formed gate, the gate insulation layer covering the pre-formed gate; depositing and forming an amorphous silicon layer, a doped amorphous silicon layer including at least three doped layers, and a metal layer on the gate insulation layer in sequence, doping concentrations of the at least three doped layers of the doped amorphous silicon layer increasing from bottom to top; etching patterns of the amorphous silicon layer, the doped amorphous silicon layer and the metal layer to form the array substrate.