Before revision: This, in turn, is composed of two components - gate to source leakage, which is leakage directly though the gate insulator, mostly by tunnelling, and source-drain leakage attributed to both tunnelling and sub-threshold conduction.
After revision: This, in turn, is composed of two components - gate to source leakage, which is leakage directly through the gate insulator, mostly by tunnelling, and source-drain leakage attributed to both tunnelling and sub-threshold conduction.