Curent suppression in Al0.35Ga0.65As‐GaAsN‐pheterojunctions is observed experimentally. The data are explained by examining the carrier transport modified by electron accumulation in the interface potential notch resulting from the conduction‐band discontinuity. In addition, it is found that the temperature dependentI‐Vmeasurements can be used to deduce the magnitude of &Dgr;ECat the junction interface.