The objective of this research is to develop an integrated lab-on-a-chip type device for multi-domain characterization of nanoscale thin films of electronic materials. The approach is to nanofabricate a 3 mm x 3mm x 0.5 mm size device with multi-functional capabilities, such as force and displacement sensors and actuator for mechanical properties and micro-electrodes for electrical and thermal conductivity characterization.
Intellectual Merits: The lab-on-a-chip tool will transform the current paradigm (single-domain characterization) to truly simultaneous multi-domain transport studies on nanoelectronic materials. The PI proposes that at the nanoscale, mechanical strain breaks down the conventional rules for scattering of electrons and phonons, giving rise to unprecedented coupling among physical domains. The PI will explore the role of extremely small length-scales on such coupling. The concept of extreme dimension-induced coupling will transform the current understanding in materials physics by removing the pre-requisite that special arrangement of atoms are required to exhibit any coupling (such as only centro-symmetric atoms lead to piezo-electricity) and thereby open a new area of multi-physics of materials.
Broader Impacts: By enabling challenging cross-cutting experimental studies, the research will bridge the existing wide gap between theoretical and experimental studies on nanostructures. The scientific findings of this research will open the area of dimension and strain tunable electron and phonon transport in next generation nanoelectronic devices. The research will be integrated to education by developing education modules at the graduate level, hiring under-represented undergraduate research assistants and performing outreach activities in the State College area school District K-12 classes.
The ever-continuing trend in miniaturization in micro-electronics and the rapid development of nanoscale materials for energy applications have added to the burden of characterization. This is because materials with length-scale of 50 nm and below exhibit properties that cannot be extrapolated from the bulk or microscale values. Off all the physical domains, electrical properties are relatively easier because they can be supported by an insulating substrate. Unfortunately, the same is not true for mechanical or thermal properties, where it may be impossible to isolate the stress or heat from the substrate. What makes it worse is that below 50 nm length-scale, mechanical or thermal properties cannot be ignored even for a purely electronic device. Perhaps the best example is the overheating of the modern computer chips and the resulting thermo-mechanical loading and reliability concerns. We present experimental techniques for measuring mechanical (stress-strain, fracture, fatigue, high temperature), thermal (conductivity and interfacial thermal conductance) and electrical (conductivity, bandgap, dielectric breakdown) properties of materials with characteristic length-scale of 50 nm or lower. The specimens are freestanding, which eliminates the possibility of errors coming from the substrate. In addition, the experimental setup is only 3mm x 5mm in size, which makes it adaptable to virtually any form of microscopy. We demonstrate this with the most difficult type – the transmission electron microscope (TEM) that has the smallest chamber, but also allows us to ‘see’ the internal microstructure and defects at up to atomic resolution. The project has partially supported 3 PhD students, one of them is female. One of them is now an Assistant Professor, and another has similar aspirations. They are trained with state of the art in nanofabrication, electron microscopy and electrical/thermal/mechanical characterization at the nanoscale. The products of this project are 13 journal journal papers, 1 provisional patent and dissemination through major international conference presentations and seminars to universities, national labs and industry. Outreach activities were performed in local middle and elementary schools to promote science and engineering education through hands on activities
