NOVELTY - The rectifier has a barrier layer (300) grown on a substrate (100). A positive electrode comprises a first portion (711) and a second portion (712). The first portion of the positive electrode is located on an upper surface of a p-type two-dimensional electron gas (2DEG) depletion layer (501). The second portion of the positive electrode is in contact with an upper surface of the barrier layer not covered by the 2DEG depletion layer. The second portion of the positive electrode and a negative electrode (702) are respectively provided on two sides of the 2DEG depletion layer.    USE - Gallium nitride-based Schottky barrier diode rectifier for use in various applications. Uses include but are not limited to power supply management, wind power generation, a solar energy battery and an electric vehicle.    ADVANTAGE - The rectifier makes a channel to be turned on at different forward voltage by changing doping concentration of a P-gallium nitride layer or p-aluminum gallium nitride layer to cause the rectifier to make two-dimensional electron gas recovery so as to adjust forward turn-on voltage of a Schottky diode. The rectifier provides the p-gallium nitride layer or the p-aluminum gallium nitride layer to be formed with an aluminum gallium nitride/gallium nitride pn junction structure so as to effectively reduce Schottky diode reverse leakage current and improve breakdown voltage of the Schottky diode when the Schottky diode is in reverse bias. The rectifier produces an injection hole to provide current shunt effect when forward voltage suddenly increases and exceeds pn junction forward turn-on voltage, so that the rectifier is prevented from being burned in a case of sudden increase in total current.    DETAILED DESCRIPTION - An INDEPENDENT CLAIM is also included for a method for manufacturing a GaN-based Schottky barrier diode rectifier.    DESCRIPTION OF DRAWING(S) - The drawing shows a cross sectional view of a gallium nitride-based Schottky barrier diode rectifier.    Substrate (100)    Barrier layer (300)    P-type 2DEG depletion layer (501)    Negative electrode (702)    Portions of positive electrode (711, 712)