To reduce drain leakage current, carbon doping is introduced in the GaN layer of the p-GaN HEMT device. The focus of this study is on the discussion of the abnormal current behavior that occurs in the saturation region of carbon-doped p-GaN HEMT. This abnormal phenomenon disappears when the device is heated up to 150°C. The abnormal current behavior corresponds to the hot electron stress (HES) result, which indicates that electron trapping causes this abnormal current behavior. An energy band is proposed to describe the lesser trapping effect that occurs in the saturation region.