Chemistry Seminar Series: Arokia Nathan

Wednesday, June 12, 2019 2:00 pm - 2:00 pm EDT (GMT -04:00)

Electronics for Organic Displays and Ultralow Power Sensor Interfaces

Arokia Nathan
Chief Technical Officer, Cambridge Touch Technologies
Cambridge, UK

Wednesday,  June 12, 2019
2:00 p.m.
C2-361 (Reading Room)

Abstract: Oxide semiconductors are a new generation of semiconductors for display electronics in view of their high transparency, low temperature processing, and low fabrication cost. Although this family of materials is optically transparent, the presence of oxygen deficiency defects, such as vacancies and interstitials, located at sub-gap states, and their ionization under illumination, leads to absorption of blue and green photons. At higher energies, we have the usual band-to-band absorption. In particular, the oxygen defects remain ionized even after illumination ceases, leading to persistent photoconductivity, which can limit the frame-rate of active matrix arrays. Despite material weaknesses, considerable progress has been made in designing large area transparent systems, following good physical insight of the underlying transport mechanisms in the transistor and in particular, the associated density of states and field-effect mobility. Part of this talk will address the design approaches employed for operationally stable organic light emitting displays, in which we will review the dark- and wavelength-dependent photo-instability and their origins, along with its unique density of states profile and the relative dominance of trap-limited conduction and percolation transport. In particular, in wearable devices the quest for low power becomes highly compelling. We will discuss transistor operation in the different regimes, and review device properties when operated in the deep sub-threshold regime or in near-OFF state, addressing the pivotal requirement of low supply voltage and ultralow power leading to potentially battery-less operation.

Professor Arokia Nathan leads a multi-disciplinary research group whose primary focus is on the heterogeneous integration of materials and processes, sensors, energy harvesting and storage devices pertinent to wearable technologies. Formerly the Chair Professor of Photonic Systems and Displays at the University of Cambridge, he is currently the Chief Technical Officer of Cambridge Touch Technologies, a company spun out of his Labs at Cambridge University developing advanced interactive technologies. He has published over 600 papers in the field of sensor technology and CAD, and thin film transistor electronics, and is a co-author of four books. He has over 110 patents filed/awarded and has founded/co-founded four spin-off companies. He serves on technical committees and editorial boards in various capacities. He is a Chartered Engineer (UK), Fellow of the Institution of Engineering and Technology (UK), Fellow of IEEE (USA), and an IEEE Electron Devices Society Distinguished Lecturer.