Choice of quantum dot materials for fabricating memory devices with longer storage and faster writing of information

摘要

We present theoretical modelling and simulation approach for studying the electron and hole dynamics in various Ⅲ-Ⅴ quantum dot (QD) device systems for high performance memory applications. A rigorous computation is carried out by developing a self-consistent Schroedinger Poisson solver for obtaining the potential state of the QD for various applied voltages of the device. A detailed capture as well as emission mechanism of the carriers is elucidated at various operating temperatures ranging from 10 to 300 K. Our results showed suitability of holes in GaSb/GaAs dots for 107 times increase in the duration of data storage and 34 times faster writing capability as compared to InAs/GaAs QDs at room temperature operation. A trade-off is necessary between extending the storage time and increasing the write time by incorporation of high bandgap AlAs barrier. However, a technique is proposed to avoid the trade-off and minimize the write and erase time along with longer storage of data for QD memories with barrier layers. Our computation also reveals greater retention capacity of electrons over holes when localized to the same potential barrier. Applications of these QDs at cryogenic temperatures are also elucidated. Thus, based on our comparative analysis, valuable information is being provided to the device scientist in choosing suitable quantum dot material for memory devices and optimizing its performance.