Embodiments of structures and methods for determining operating characteristics of a non-volatile memory transistor comprising a charge-storage-layer and a tunneling-layer are described. In one embodiment, the method comprises: forming on a substrate a structure including a nitrided tunneling-layer and a charge-storage-layer overlying the tunneling-layer comprising a first charge-storage layer adjacent to the tunneling-layer, and a second charge-storage layer overlying the first charge-storage layer, wherein the first charge-storage layer is separated from the second charge-storage layer by a anti-tunneling layer comprising an oxide; depositing a positive charge on the charge-storage-layer and determining a first voltage to establish a first leakage current through the charge-storage-layer and the tunneling-layer; depositing a negative charge on the charge-storage-layer and determining a second voltage to establish a second leakage current through the charge-storage-layer and the tunneling-layer; and determining a differential voltage by calculating a difference between the first and second voltages.