Nitridization of GaAs surfaces by exposure to a nitrogen or nitrogen‐hydrogen plasma is known to form a surface coating rich in GaN. We show that pretreatment in a hydrogen plasma at room temperature followed by production of this wider band‐gap material by nitrogen plasma treatment at 500 °C for 5 h reduces the reverse leakage current of Au‐GaAs (ND−NA=5×1017cm−3) Schottky diodes by typically an order of magnitude at 300 K.