Optoelectronic microwave semiconductor memories: performance advantages over traditional semiconductor memories

DRAM (Dynamic Random Access Memory) is widely used in computers due to high speed, high packing density, and low cost. Functions of DRAM rely heavily on sensing techniques, as the stored charges leak all the time, even during the normal memory operations, such as READ, which destroys the bit and an immediately refresh must be followed after sensing. For these reasons, the storage capacitor of DRAM needs to be as large and packed as possible, which are trade-off conditions, and sophisticated, costly 3D fabrication is required. Photonic DRAM eliminates the needs of many refresh cycles. For example, the DRAM READ operation is done with ultra short duration pulsed laser sensing, bypassing the time assuming sensing with electron charging and discharging, which must release the stored electrons and destroy the bit. Microwave Photonic CMOS Technology is implemented as the DRAM Word Line Transistors. Traditionally, the Word Line MOSFET is relatively slow, in order to reduce the leakage of the stored electronics in the storage capacitor. Photonic MOSFETs improve the speed of the Word Line, with laser generated light carriers. The sense amplifiers and DRAM circuits are also much faster. In recent years, Vertical NAND FLASH has replaced NOR FLASH in most of the hand held wireless digital markets, due to advantages of lower cost, higher packing density, and higher speed. However, the speed of NAND FLASH is still behind DRAM and SRAM used in computing tools, caused by the dielectric trapping, and tunneling processes, which result in longer WRITE and ERASE cycles. In this report, we will demonstrate an ultra-high-speed Photonic Vertical NAND FLASH with multiple VCSELs (Vertical Cavity Surface Emitting Laser), that may outperform DRAMs due to lower voltages and much faster nonvolatile memory operations. The new capability of integrated arrays of VCSELs with the high-speed Vertical Photonic NAND FLASH for lasing and nonvolatile data storage can be achieved.