Evidence of long-term storage of minority carriers in N+-GaAs/AlGaAs/P-GaAs MIS capacitors

We have investigated the long-term retention of electrons in potential wells at the AlGaAs/GaAs interface at 77 K. By analyzing the steady-state capacitance-voltage (CV) and current-voltage (I-V) characteristics of N+-GaAs/AlGaAs/P-GaAs MIS capacitors under illumination, we can calculate the leakage rate of electrons over the AlGaAs barrier as a function of the density of electrons in the well. At 77 K, we obtain storage times of 135 ms, and we estimate that the intrinsic storage time in the dark may be greater than 500 ms. These values would be suitable for the development of a one-transistor dynamic random access memory (RAM) in the MODFET technology.