Monolithic and single-functional-unit level integration of electronic and photonic elements:FET-LET hybrid 6T SRAM

A broad range of technologies have been developed for the chip and wafer scale connections and integrations of photonic and electronic circuits,although major challenges remain for achieving the single-functional-unit-level integration of electronic and photonic devices. Here we use field-effect transistor/light-effect transistor (FET–LET) hybrid 6T static random-access memory (SRAM) as an example to illustrate a novel approach that can alleviate three major challenges to the higher-level integration of the photonic and electronic elements:size mismatch,energy data rate,and cascadability. A hybrid 6T SRAM with two access FETs being replaced by LETs and the electrical word lines replaced by optical waveguides is proposed. This hybrid 6T SRAM is analyzed to reveal its potential in improvement of the switching speed and thus total energy consumption over the conventional 6T SRAM. Numerical analyses,for instance,for a prototype 64 kB hybrid SRAM array,show a factor of 4 and 22reduction in read delay and read energy consumption,and 3 and 4 in write delay and write energy consumption,respectively,when the access FETs are replaced by LETs. The potential impacts on the peripheral and assist circuits due to this hybrid structure and application of the LETs there are also briefly discussed.