At present, there are two main types of semiconductor charge storage technology. The first type is volatile storage, such as computer memory, which can write data in a few nanoseconds, but the data will disappear immediately after power failure; The second type is non-volatile storage, such as a USB flash drive. It takes several microseconds to several tens of microseconds to save data, but it can be saved for 10 years without extra energy after writing the data.
The new charge storage technology can realize a brand-new third storage characteristic: the writing speed is 1 0,000 times faster than the current U disk, and the data refresh time is10.56 times that of the memory technology. But also has good controllability, and the storage structure can be designed according to the effective time requirements of data. It not only meets the data writing speed of 10 nanosecond, but also realizes the quasi-nonvolatile characteristics of controllable data customized on demand (10 second-10 year). It can not only greatly reduce the storage power consumption in high-speed memory, but also realize the natural disappearance of data after expiration, which solves the contradiction between confidentiality and transmission for some special application scenarios.
In this study, molybdenum disulfide, tungsten selenide, hafnium disulfide, boron nitride and other two-dimensional materials are innovatively selected to form a semi-floating gate transistor, and a Van der Waals heterojunction with stepped energy valley structure is fabricated. Some are like a door that can be opened and closed at will, and electrons are easy to enter but difficult to exit; The other part is like an airtight wall, which makes it difficult for electrons to get in and out. The stipulation of "writing speed" and "non-volatile" lies in the proportion of these two parts. This important breakthrough, from technical definition, structural model to performance analysis, was independently completed by the research team of Fudan University.