15-Jul-2022: New memory device with excellent switching characteristics and low-power requirements developed

Scientists have developed a memory device with excellent switching characteristics and low-power requirements for data storage applications.

Resistive memory devices with insulating film sandwiched between electrodes can address the needs of high-performance, and high-density memories with low power requirements for data storage. They are devices with resistive switching characteristics which refers to the physical phenomena in which a dielectric (electrical insulator that can be polarised by an applied electric current) suddenly changes its (two terminal) resistance under the action of a strong current. Though such devices have been studied intensively to meet the huge technological demands in terms of performance, several technical challenges still persist and pose major challenges to their commercialization.

Extensive efforts are being made by scientists to design resistive switching-based memory devices that are non-volatile, reliable, and perform much better than the existing silicon-based flash memory technology.

Ms. Swathi S. P. and Dr. S. Angappane from the Centre 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 made from the chemical hafnium oxide, a replacement for silicon oxide, for data storage applications.

They have used hafnium oxide (HfO2), an insulator which can be polarised on application of electric current as an insulating layer. They prepared with by a method called sputtering deposition method. It is a physical vapour deposition technique in which energetic ions are used to knock off the atoms or molecules from the desired ‘target’ material and deposit them onto a substrate. The HfO2 film’s resistive switching characteristics could further be enhanced by tuning 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 the hardness to make it more workable.

The team found that a higher concentration of oxygen vacancies (loss of oxygen from their respective positions in the crystal lattice) is created when these films are subjected to heat thermal treatment process called annealing. The oxygen vacancies play a vital role in creating conditions for low power operations. Besides, thermal treatment also influenced crystalline behaviour and density of defects of the hafnium oxide films, thereby affecting resistive switching parameters and device performance. Besides, the devices also exhibited good endurance, and high retention.

Their research published in the Journal of Alloys and Compounds can contribute to the development of more efficient, viable, and reliable resistive memory devices in the future. The CeNS researchers are converting these resistive memory devices into miniature forms. The team is investigating brain-inspired functionalities in these memory devices and exploring the possibility of integrating the memory device with other potential sensors to bring out its multifunctional capabilities.

19-Apr-2022: Plasma-based green disinfectants can limit spread of infectious diseases like COVID 19

Researchers have developed a plasma-based disinfectant generated with the help of cold atmospheric pressure plasma (CAP) which could act as a green decontaminant for COVID 19.

The COVID 19 pandemic had brought forth the urgent need for decontaminants that can limit the spread of infectious diseases through contact. However, most decontaminants consisted of chemicals which are hazardous for the environment. This encouraged researchers to work towards greener alternatives.

A team of scientists Dr. Kamatchi Sankaranarayanan, Dr. Mojibur R. Khan, and Dr. H. Bailung from the Life Sciences and Physical Sciences divisions from the Institute of the Advanced Study in Science and Technology (IASST), an autonomous research Institute of the Department of Science and Technology (DST), Govt. of India, Guwahati, Assam has demonstrated that the plasma generated by cold atmospheric pressure (CAP) has the potential to deactivate SARS-CoV-2 spike protein, which binds to human ACE2 receptor for inducing viral infection and subsequent Covid-19.

Plasma, the fourth state of matter which makes up most of the universe when produced in controlled conditions in the lab and are termed as Cold Atmospheric Pressure Plasma (CAP). The scientists passed plasma forming gases such as Helium, Argon, and Air through a high voltage electric field which led to the formation of a stable plasma with a mixture of ions, and electrons emitting a pink glow of CAP inside the reaction chamber.

This research recently published in the international journal of the RSC (Royal Society of Chemistry) Advances shows that short-lived highly reactive oxygen and nitrogen species (ROS/RNS) generated in the plasma led to complete deactivation of the SARS-CoV-2 Spike protein occurs within 2 min of CAP treatment. The RT-PCR analysis has also established that CAP can deactivate the RNA of the SARS-CoV-2 virus.

The researchers showed that the CAP, a plasma-based disinfection method is a better alternative to environmentally hazardous chemical-based decontamination methods. “The cold atmospheric plasma is environmentally safe since, during the entire decontamination process by plasma treatment, no chemical waste is produced.

The lead authors Dr. Kamatchi Sankaranarayanan and Dr. H. Bailung said that the disinfection method could further be extended for various bacterial or fungal infections.

The research was conducted at the Covid-19 testing and research facility of IASST which according to Director Prof. Ashis K. Mukherjee has carried out more than 1.54 lakhs tests till date.