| AVS 65th International Symposium & Exhibition | |
| Electronic Materials and Photonics Division | Thursday Sessions |
| Session EM+MI+MN+NS-ThM |
| Session: | Nanostructures for Electronic and Photonic Devices |
| Presenter: | Ryan Ley, University of California at Santa Barbara |
| Authors: | R.T. Ley, University of California at Santa Barbara C.D. Pynn, University of California at Santa Barbara M. Wong, University of California at Santa Barbara S.P. DenBaars, University of California at Santa Barbara M.J. Gordon, University of California at Santa Barbara |
| Correspondent: | Click to Email |
The III-Nitrides are excellent materials for LEDs, lasers and power electronics due to their tunable bandgap and high defect tolerance. These materials are increasingly important for displays in mobile and portable electronic devices, which currently suffer from short battery lives because displays based on liquid crystals or organic LEDs are inefficient. Producing high quality III-Nitride material with the indium compositions needed for efficient green and red emission is presently very challenging, due in large part to strain effects resulting from the large lattice mismatch between InGaN and GaN. However, there are some indications that nanostructuring can reduce or eliminate some of these strain issues.
This talk will highlight our recent work using colloidal and templated lithography and Cl2 /N2 plasma etching to fabricate nanoscale InGaN/GaN LED structures (diameter = 150-600nm), and how sub micron scale patterning affects the strain state and optical behavior of MQW emitters. InGaN/GaN LED structures were grown by MOCVD on c-plane sapphire substrates and characterized before and after nanopatterning using on-axis (0002) and off-axis (10-15 and 11-24) XRD reciprocal space maps (RSM), rocking curves and photoluminescence (PL) spectroscopy at 14K. RSM analysis found degrees of relaxation of 30% and 20% for the smallest and largest structures, respectively, and rocking curves revealed a 0.7nm decrease in the InGaN quantum well thickness. These relaxation effects also correlate well with spectral blue shifts (∼10-15nm) in the PL, which are supported by 1D quantum mechanical and electrostatic simulations. Overall, this work shows that nanopatterning of InGaN/GaN active emitters at sub-micron length scales can reduce strain related issues in the III-Nitrides and potentially allow higher incorporation of indium for green and red emission.