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So, I understand of the NMOS transistor work's here (at least I believe I do). Electrons are flowing towards the capacitor plate from the drain here. So, I don't get how the plate connected to the drain is positively charged instead of being negatively charged. Can someone explain?
The transistor is symmetrical, and used as a switch. Pull the gate positive, and the N channel goes to a conductive state. The voltage on the top of the capacitor thus duplicates the voltage on the bit line to the left. The voltage at the bottom of the capacitor is held constant by its connection to the substrate (its bottom plate is the chip substrate).
If, during this operation, the bit line is forced high or low, the corresponding voltage is stored on the capacitor (write operation). If it's not forced, the voltage on the capacitor influences the voltage on the bit line, and this may be sensed (read operation).
Did you notice that I didn't use the word "electron"? Tracking electrons is often more confusing than illuminating. Pay attention to voltages and currents. The only place it might be useful to think about electrons is in understanding why a positive voltage on the gate turns on the N-channel transistor.
