In previous blogs, two dimensional semiconductors have been discussed. Work at Singapore University of Technology and Design has developed a different approach to solving the issues of very small transistors that will be required for future generations of semiconductors [Ref. 1]. Their work demonstrated that the 2D semiconductors using MoSi2N4 and WSi2N4 form Ohmic contacts with titanium, scandium and nickel. These structures are free from Fermi Level Pinning (FLP), which is present in other 2D semiconductors. Their approach to minimize the FLP requires a precise positioning of the metal on top of the semiconductor, which employs the 2D metal as contact material. Their material is shielded due to the formation of an inert Si-N layer shielding the semiconductor layer from defects and material interactions at the contact interface. They are planning to employ computer evaluations of similar materials to determine other potential materials.
Work is continuing to find improved material for Chemical energy, which could provide storage via chemical energy that can be converted into mechanical energy. Chemical energy is a term for the energy stored in covalent bonds holding atoms together in molecules. Work accomplished at the University of Buffalo, University of Maryland and Army Research Labs evaluated the potential of combining energic materials with ferroelectrics to create a high power density energy source that would be chemically driven. The reported results are that two dissimilar materials (molecular energetic materials and ferroelectrics) can be combined to obtain chemically created electrical energy with a specific power of 1.8kW/kg. Employing a polarization of molecular energetic ferroelectrics can provide control of both the energy density and the rate of energy release.
Work at Northwestern University and Argonne National Labs has developed a material that is four atoms thick and allows the evaluation of charged particle motion in only two dimensions [Ref. 3]. The target material was a combination of silver, potassium, and selenium. Heating this material to over 450F, it became a relatively symmetrical layered structure. Before the heating, the silver ions were fixed within the two dimensional material. After the transition due to heating, the silver atoms had small movement. This discovery has the potential to provide a platform for the evaluation of materials that could be constructed to have both high ionic conductivity and low thermal conductivity. One of the potential outcomes is the ability to develop membranes that could provide environmental clean including desalting of water.
A team of researchers at the University of Florida and Florida Institute of Technology have produced a high-efficiency mechanical signal amplification in nanoscale resonators operating at radio frequencies [Ref. 4]. The researchers observed parametric amplification in nanoscale devices. The device contains a nanoscale drumhead mechanical amplifier consisted of a two dimensions semiconducting molybdenum disulfide membrane with drum head thickness of 0.7, 2.8, and 7.7 nanometers. The drum head was 1.8 microns in diameter with a volume of 0.020 m3. The drum head was fabricated by transferring nanosheet exfoliated from bulk crystals over microcavities to make the thin nanodrums. Amplification gains of up to 3600 were obtained. This process can be employed in developing nanoscale sensors and actuators.
What we are witnessing is the development of new materials that have been able to be developed due to the ongoing research in nanotechnology and the resultant development of tools for analysis of the various materials.