Light-weight and robust ultraviolet (UV) light emitting sources find potential applications in water purification, bio sensors, solid state lighting and lithography. Direct-bandgap III-Nitride semiconductors exhibit bandgap energies extending upto 6.2 eV (210 nm, deep UV) and are thus attractive to realize UV LEDs. But as the Al composition is increased to reach shorter wavelengths, the internal quantum efficiency (IQE) severely degrades due to the valence band asymmetry, high threading dislocation densities, quantum-confined Stark-effect, and inefficient n- and p-type doping. To mitigate the adverse effects of such factors and to boost the IQE, we proposed and demonstrated a new design that incorporates ultra-small GaN quantum dots (QDs) in AlN barriers along with polarization doped p-AlGaN layers, and uses quantum mechanical tunneling to inject and transfer carriers through the active region. The novel LED design produces emission at 240 nm and improves the UV light intensity > 20 times. The successful demonstration paves the way for efficient LEDs and laser diodes (LDs) in the short-wavelength regime, which remains an unconquered territory.
Jai Verma is a 2013 PhD graduate from University of Notre Dame. His research interests lay 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. After graduation he worked as a research assistant professor at University of Notre Dame for a period of one year. Currently he is employed at Intel corporation as Yield Engineer. During his time at Notre Dame he worked 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. His work at Intel corporation is develop and drive process improvements on material and equipment to meet quality, reliability, cost, yield, productivity and manufacturability requirements.. He has published >40 papers in noted scientific journals and conferences.