by Prof. Ion Tiginyanu
08.12.2016, 17:00 h, TF, Aquarium
Gallium Nitride is considered nowadays the second most important semiconductor material. Over the past decades it has played a major role in the development of modern solid-state lighting industry. For their significant contribution to this success, Shuji Nakamura, Isamu Akasaki and Hiroshi Amano were awarded the Nobel Prize for Physics in 2014. At present GaN continues its impactful evolution in various fields, exhibiting a new exceptional take off. In particular, the first room-temperature electrically-pumped inversionless polariton laser based on GaN microcavity diode has been recently demonstrated, while in micro-nanoelectronics gallium nitride is becoming a cornerstone for semiconductor power electronics, enabling orders-of-magnitude higher switching frequency of electronic devices under simultaneous lower energy consumption in comparison to silicon. In this presentation, we report on a novel technology, called Surface Charge Lithography (SCL), allowing direct writing of gallium nitride micro- and nanostructures. The proposed technological route comprises low-dose focused ion beam direct writing of micro-nanostructures and subsequent photoelectrochemical etching. Under specific conditions, SCL proves to be a powerful tool for the fabrication of ultrathin GaN suspended membranes promising for nanoelectronic applications, in particular in high-power memristive devices or memristor networks exhibiting novel functionalities. Besides, we show that SCL enables one to fabricate flexible photonic crystals with embedded waveguides, beam splitters and cavities. Two- and three-dimensional nanostructured architectures based on GaN have been developed for multifunctional use, some of promising applications being generated by piezoelectric characteristics inherent to GaN. A good example, in this regard, is the recently developed ultra-lightweight and flexible pressure sensor based on graphene aerogel decorated by GaN nanocrystalline films. Promising biomedical applications of GaN nanoparticles are discussed, e.g. targeted drag delivery, artificial stimulation of tissue motility, living cell targeting with piezoelectric nanoparticles etc.