Our new study showing how bolometric effect can be used to measure the thermal conductivity of nanosheets and nanowires is just accepted to IOP 2D Materials. The method relies on local heating of a nanosheet suspended over a circular hole with a focused laser beam. This results in a bolometric response on the material, i.e. the local resistivity over the suspended part changes, leading to a measurable signal when measured appropriately. Then, through modelling, the resistivity change can be calculated with thermal conductivity being a fitting parameter. The method provides a superior sensitivity as the resistivity changes as small as a part per million can be measured using a lock-in technique. This also reduces the need for the local heating making the method suitable for studying the thermal conductivity in the vicinity of the temperature induced thermal conductivity changes. Of course, like every other thermal conductivity measurement technique, there are limitations to this method as well. First of all, if there is no bolometric response from the material, such as the residual resistivity of metals at low temperature, the method doesn’t work. Also, a complicated analysis is required to study the semiconducting materials. Overall, we believe this method is a milestone in measuring the thermal conductivity of nanosheets and nanowires.
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Strongly Correlated Electron Systems
Electronic correlations, namely electron-electron interactions and electron-lattice interactions lead to exotic phenomena in solid state mater. In our lab our focus is on various aspects of strongly correlated materials. Our research begins from investigation of high quality novel materials synthesis and spans investigation of low temperature electronics and optoelectronics of novel devices.
Atomically Thin And A Few Nm Thick Transition Metal Compounds
SCMLab research begins at the synthesis level. Our main focus lies compounds of transition metals with group 6a elements. In particular we are interested in understanding the synthesis routes that lead to atomically thin transition metal dichalcogenides and VO2 nanocrystals. In our most recent effort we developed a chemical vapour deposition synthesis chamber that allows real time optical observation and control of the synthesis.
The video shows real time formation of atomically thin WSe2 crystals. This is a first ever demonstration of monolayer TMDC crystals forming in real time. Taken from our recent pre-print “Real time optical observation and control of atomically thin transition metal dichalcogenide synthesis”.
Funding: TUBİTAK 1001 #116M226
Synthesis of V₂O₃ nanoplates for exploring correlated supercritical state
Physical Review B (Rapid Communications), 100, 161107(R), 2019.
Hamid Reza Rasouli, Naveed Mehmood, Onur Çakıroğlu, Engin Can Sürmeli, T. Serkan Kasırga
Real time optical observation and control of atomically thin transition metal dichalcogenide synthesis.
Hamid Reza Rasouli, Naveed Mehmood, Onur Çakıroğlu and T. Serkan Kasırga.
Chemical vapor transport synthesis of a selenium-based two-dimensional material.
Turkish Journal of Physics, 42(3):293-301, 2018.
T. Serkan Kasırga.
Optoelectronics Of Strongly Correlated Materials
Using scanning photocurrent microscopy method, we investigate optoelectronics of strongly correlated materials. Recently, we started working on low temperature optoelectronics of layered transition metal dichalcogenides.
Funding: TUBİTAK 1001 #214M109 & #118F061
Thermal Conductivity Measurements in Nanosheets via Bolometric Effect
2D Materials, Accepted, 2020
Onur Çakıroğlu, Naveed Mehmood, Mert Miraç Çiçek, Aizimaiti Aikebaier, Hamid Reza Rasouli, Engin Durgun, T. Serkan Kasırga
Photoresponse of a strongly correlated material determined by scanning photocurrent microscopy.
Nature Nanotechnology, 7:723-, 2012.
T. Serkan Kasırga, Dong Sun, Jae H. Park, Jim M. Coy, Zaiyao Fei, Xiaodong Xu and David H. Cobden.