Before revision: Diffusion Capacitance is the capacitance that happens due to transport of charge carriers between two terminals of a device, for example, the diffusion of carriers anode to cathode in a forward biased diode or from emitter to baseforward-biased junction of a transistor.The «forward biased» in this context means that that the diode/transistor allows the current to flow.
After revision: fromDiffusion Capacitance is the capacitance that happens due to transport of charge carriers between two terminals of a device, for example, the diffusion of carriers anode to cathode in a forward biased diode or from emitter to baseforward-biased junction of a transistor.The «forward biased» in this context means that that the diode/transistor allows the current to flow.