Laser-Assisted Multilevel Non-Volatile Memory Device Based on 2D van-der-Waals Few-Layer-ReS2/h-BN/Graphene Heterostructures

Few-layer rhenium disulfide (ReS2) field-effect transistors with a local floating gate (FG) of monolayer graphene separated by a thin hexagonal boron nitride tunnel layer for application to a non-volatile memory (NVM) device are designed and investigated. FG-NVM devices based on two-dimensional van-der-Waals heterostructures have been recently studied as important components to realize digital electronics and multifunctional memory applications. Direct bandgap multilayer ReS(2)satisfies various requirements as a channel material for electronic devices as well as being a strong light-absorbing layer, which makes it possible to realize light-assisted optoelectronic applications. The NVM operation with a high ON/OFF current ratio, a large memory window, good endurance (>1000 cycles), and stable retention (>10(4)s) are observed. The successive program and erase states using 10 ms gate pulses of +10 V and -10 V are demonstrated, respectively. Laser pulses along with electrostatic gate pulses provide multibit level memory access via opto-electrostatic coupling. The devices exhibit the dual functionality of a conventional electronic memory and can store laser-pulse excited signal information for future all-optical logic and quantum information processing.