MBE grown Quantum-Dot UV Light Emitting Diodes with Tunnel-injection and Polarization-engineering

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Dept of EE announces an IEEE Seminar
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Jai Verma,
University of Notre Dame

will speak on

"MBE grown Quantum-Dot UV Light Emitting Diodes with Tunnel-injection and
Polarization-engineering"

Where: DA 229, ACES Building, Dept of Electrical Engg.
When: Tuesday, January 22, 2013
What Time : 5 PM
Refreshments will be served at 4:45 PM

Abstract:
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Immense progress has been made in III-Nitride optical devices since the demonstration of blue lasers in mid 90’s. The attention of the solid state lighting has shifted to longer wavelength (green), and to short wavelength (UV). At the same time, major challenges remain in improving the efficiency of III-Nitride optical emitters. In this work, we explore the many consequences of the electronic polarization fields at heterojunctions of very short-λ light emitters. By using molecular beam epitaxy, we grow III-Nitride heterostructures with high Al-composition AlGaN on AlN substrates for UV emitters. A careful analysis of the role of polarization in heterostructures enables us to design and demonstrate novel N-face QW LED heterostructure that incorporates polarization-induced doped p-type layers. These QWs emit photons near GaN QW band gap at room temperature. For shorter-λ emission, we design and demonstrate a novel quantum-dot UV LED that uses tunnel-injection of carriers. This Q-dot UV LED emits at room temperature at ~240 nm. Both demonstrations help us identify unique opportunities for improvements in short-wavelength III-Nitride LEDs and lasers of the future. These compact light emitters are expected to enable numerous optoelectronic applications, specifically those that lead to bio-photonic applications.

Biography:
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Jai Verma is a PhD candidate at University of Notre Dame. His research interests are in Molecular Beam Epitaxy growth, fabrication and analysis of III-Nitride based optoelectronic devices. He received his Bachelor’s and Master’s degrees in Electrical Engineering from the Indian Institute of Technology Kanpur in 2008 where he had worked on P3HT:PCBM based organic solar cells. More recently he has been working on boosting the efficiency of III-Nitrides Ultra-Violet Light Emitting diodes (UV LEDs) utilizing novel structures comprising of polarization induced doping, tunnel injection and quantum dots. His research interests also include Transmission Electron Microscope analysis of III-Nitride device structures. He has published 24 papers in noted scientific journals and conferences.

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Refreshments will be served at 4:45 PM.

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