Nanoscale Chemical Characterization of Novel Semiconductor Materials using Tip-Enhanced Optical Spectroscopy
Dr. Naresh Kumar
Senior Scientist
Department of Chemistry and Applied Biosciences, ETH Zurich
*The organization and the title are those when awarded
Research summary
Dr. Naresh Kumar’s research focuses on the nanoscale investigation of two classes of semiconductor materials: two-dimensional (2D) transition metal dichalcogenides (TMDs) and organic photovoltaic (OPV) devices. In the study of 2D TMDs, Dr. Kumar utilized tip-enhanced optical spectroscopy (TEOS) to investigate excitonic processes in single-layer (1L) MoS2 and WSe2. Through hyperspectral tip enhanced photoluminescence imaging, he demonstrated an unprecedented spatial resolution of 20 nm in mapping exciton and trion populations in 1L MoS2. In the case of 1L WSe2, Dr. Kumar combined TEOS with Kelvin probe force microscopy to reveal the optoelectronic behavior of grain boundaries (GBs) at a resolution of 50 nm. For OPV devices, Dr. Kumar introduced a novel methodology called simultaneous topographical, electrical, and optical microscopy (STEOM) by combining TEOS with photoconductive-AFM (PC-AFM). This innovative approach enabled the simultaneous characterization of topography, chemical composition, and photoelectrical properties of an operational OPV device with sub-20 nm resolution.
The significance of Dr. Kumar’s research lies in the advancements made in nanoscale characterization and understanding of novel semiconductor materials. He has expanded the capabilities of TEOS by applying it to 2D TMDs and OPV devices, surpassing the limitations of conventional techniques. His findings provide valuable insights into excitonic processes, heterogeneity of exciton and trion populations, optoelectronic behavior of GBs, and the structure property relationships in OPV devices. Dr. Kumar’s research on the development of novel nanoanalytical technologies is expected to contribute significantly to the development and optimization of next-generation optoelectronic devices and organic photovoltaic technologies.
The significance of Dr. Kumar’s research lies in the advancements made in nanoscale characterization and understanding of novel semiconductor materials. He has expanded the capabilities of TEOS by applying it to 2D TMDs and OPV devices, surpassing the limitations of conventional techniques. His findings provide valuable insights into excitonic processes, heterogeneity of exciton and trion populations, optoelectronic behavior of GBs, and the structure property relationships in OPV devices. Dr. Kumar’s research on the development of novel nanoanalytical technologies is expected to contribute significantly to the development and optimization of next-generation optoelectronic devices and organic photovoltaic technologies.
Introduction to Research
