Scientists have developed a memory device with excellent switching characteristics and low power requirements for data storage applications.
Resistive memory devices with an insulating film sandwiched between the electrodes can meet the needs of high performance, high density memories with low power requirements for data storage. They are devices with resistive switching characteristics which refer to the physical phenomena in which a dielectric (electrical insulator which can be polarized by an applied electric current) suddenly changes its resistance (at two terminals) under the action of a strong current. Although such devices have been studied intensively to meet the enormous technological demands in terms of performance, several technical challenges persist and pose major challenges to their commercialization.
Considerable efforts are being made by scientists to design resistively switched memory devices that are non-volatile, reliable, and far superior to existing silicon-based flash memory technology.
Ms. Swathi SP and Dr. S. Angappane from Center for Nano and Soft Matter Sciences (CeNS), Bangalore, an autonomous institution of Department of Science and Technology, Govt. of India (DST), have developed a low-power memory device with excellent switching characteristics based on chemical hafnium oxide, a silicon oxide substitute, for data storage applications.
They used hafnium oxide (HfO2), an insulator that can be polarized when an electric current is applied as an insulating layer. They prepared with a method called the sputter deposition method. It is a physical vapor deposition technique in which energetic ions are used to remove atoms or molecules of the desired “target” material and deposit them onto a substrate. The resistive switching characteristics of HfO2 film could be further improved by adjusting the growth temperature and annealing conditions – a heat treatment process that changes the physical and sometimes chemical properties of a material to increase ductility and reduce hardness for make it more manageable.
The team found that a higher concentration of oxygen vacancies (loss of oxygen from their respective positions in the crystal lattice) are created when these films are subjected to a heat treatment process called annealing. Oxygen gaps play a critical role in creating the conditions for low power operations. In addition, heat treatment also influenced the crystal behavior and defect density of hafnium oxide films, thereby affecting resistive switching parameters and device performance. In addition, the devices also exhibited good endurance and high retention.
Their research published in the Journal of Alloys and Compounds may contribute to the development of more efficient, viable and reliable resistive memory devices in the future. CeNS researchers are converting these resistive memory devices into miniature forms. The team is investigating brain-inspired functionality in these memory devices and exploring the possibility of integrating the memory device with other potential sensors to bring out its multifunctional capabilities.
(With GDP entries)