Time Dependence of Charge Transport in MIS Memory Transistors

Based on the direct tunneling model, the complete solution is obtained for the charge-transport equation for MIS memory transistors. It is shown that the time dependence is linear in the microsecond range, roughly logarithmic in the millisecond range, and eventually saturates to a value determined by the physical characteristics of the device. For an oxide layer 20 Å thick, the theory predicts a switching time of about 45 μsec and saturation in about 150 sec.