Optical absorption and charging effect in nano-crystalline Ge/SiNx multilayers

Nanocrystalline Ge (nc-Ge)/SiNx multilayers and sandwiched structures were fabricated by thermally annealing amorphous Ge/SiNx layered films at 600 °C. The evolution of microstructure before and after annealing was studied by various characterization techniques, which reveals the formation of nc-Ge after annealing. The tunable optical absorption and band gap were observed by changing the grain size of nc-Ge. The study on carrier transport behavior of nc-Ge/SiNx MLs indicated that the transport process was dominated by space-charge limited current mechanism. Furthermore, the charging storage effect in SiNx/nc-Ge/SiNx floating gate structures was demonstrated due to both the electron and hole injection processes.