Nanostructured sensor, solar cell and resistive memory devices

Oct26Fri

Nanostructured sensor, solar cell and resistive memory devices

Fri, 26/10/2012 - 10:30

Location:

Speaker: 
Professor Bodh Raj Mehta, Schlumberger Chair Professor of Semiconductor Physics
Affiliation: 
Indian Institute of Technology Delhi, New Delhi, India
Synopsis: 

The unprecedented research interest in the nanoscience and technology stems from the size dependent properties and improved devices characteristics of nanoscale materials and devices. In this presentation, some examples from our research will be discussed.
Deposition of nanoparticle having controllable size, well defined size distribution, composition is crucial to understanding and realizing size dependent properties. A nanoparticle deposition facility comprising of particle synthesis system, UV charger, differential mobility analyzer, in-flight sintering, nanoparticle deposition onto substrates along with on-line size distribution measurements has been used for growing monosized and spherical metal nanoparticles. Metal, alloy and core-shell nanoparticles prepared by this method have been used for a number of studies: Pd, Pd-Cu and Pd-Ag alloy nanoparticles for hydrogenation properties, Ag-Cu nanoparticle plasmonic layers and Pd-C core-shell nanoparticles for magnetic applications.
With the objective of understanding the photovoltaic response of nanorod based solar cells, studies of determining photoconducting, photovoltaic response and Kelvin probe microscopy of single semiconductor heterojunction nanorods has been carried out. A complete reversal of photoconducting response in CdS nanorods having 20 nm diameter is observed. Photovoltaic response of single nanorod CdS-Cu2S and CdS-CdTe heterojunctions has been studied in terms of solar cell parameters, shift of Fermi level, interface layer formation within different regions of the nanorod.
Investigations carried out on devices formed with hexa-peri-hexabenzocoronene (HBC), 6F-HBC and Graphene monolayer materials incorporated at metal- oxide junctions show that resistive switching varies from unipolar to bipolar. A detailed CAFM investigation of resistive memory cells having different dimensions show that the macroscopically measured resistive switching parameters are related to the distribution in size and current level of the filaments in ‘on and ‘off’ states. This study sets the foundation for fabricating nanoscale resistive switching devices.

Biography: 

Bodh Raj Mehta is currently Professor of Physics and Schlumberger Chair professor of Semiconductor Physics at Indian Institute of Technology Delhi, New Delhi, India. He did his M Sc in Physics from Punjabi University Patiala, M Tech in Solid State Materials and Ph D in Physics from IIT Delhi. He has worked as post-doctoral fellow at University of British Columbia, Canada; guest scientist at University of Saarbrucken, Germany; and guest professor at University of Duisburg, Germany. He has about 25 years experience in teaching and research. His major research interests are; Science and Technology of Thin Films and Nanostructured Materials for Solar Cell, Resistive Memory, Thermoelectric and Gas Sensor Devices. He is the recipient of MRSI Medal (Material Research Society of India, 2002), DAAD Fellowship (Deutscher Akademischer Austausch Dienst, 2000) and Marie Curie International Fellowship (European Commission, 2006). He is on the Editorial Board of Journal of Nanoscience and Nanotechnology and has about 160 journal publications. He is the Coordinator of the ‘Unit on NanoScience’ (Nanomission) at IIT Delhi; Co-coordinator of Nano Research Facility at IIT Delhi. One of his projects ‘NanoSwitch’ has been selected by European Commission as a ‘Success Story’ project.

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