Growth of low defect density III-N on Nanowires S. M. Bedair, North Carolina State University, DMR Gallium Nitride (GaN) is a pivotal material system for both light-emitting diodes (LEDs) and power electronic devices; however, a high density of defects in epitaxially grown GaN is one of the current issues facing GaN based devices. We have previously demonstrated that defect density in epitaxial GaN can be reduced by the deposition of GaN on GaN on nano wires (NWs). We have achieved two major developments in for improved quality of GaN LED structures. –Firstly, we have demonstrated GaN NWs by maskless hot phosphoric wet-etching of nitrogen-face (N-face) GaN. These NWs are advantageous because they are created without the use of a mask or ion-etching equipment and can reduce the dislocations density in the subsequent GaN layers. –We have also demonstrated a N-face LED with an inversion layer. The inversion layer is necessary for MOCVD grown N-face LEDs, as it both improves the surface morphology and also aids in magnesium doping of the p-type layer, which is necessary for LED structures. Without the inversion layer, we could not achieve the p-type doping necessary on N-face GaN for LED emission. These results have contributed to furthering research in GaN defect reduction and in improving LED performance. We intend to combine these results in the coming year in order to achieve a NW LED based on chemical wet- etching of N-face GaN. * D. Bharrat, A. M. Hosalli, D. M. Van Den Broeck, J. P. Samberg, S. M. Bedair, N. A. El-Masry, Appl. Phys. Lett. 103, (2013). * A. M. Hosalli, D. M. Van Den Broeck, D. Bharrat, N. A. El- Masry, S. M. Bedair, Appl. Phys. Lett. 103, (2013). (bottom left) EL spectra of LED grown on N-face, GaN with an inversion to allow the growth of p-type GaN. The effect of injection current on the 500nm emission peak is shown. The LED behaved similarly to Ga-face LEDs with a turn- on voltage of 4.26 V. (top left) SEM image of N-face GaN etched in H 3 PO 4 at 120 °C for 2 minutes. The etch resulted in NWs with total height of about 400 nm. (top right) PL sepctra of MQW grown on NWs showed a reduced FWHM and increased emission intensity when compared to planar N-face MQW.

Foreign and Underrepresented Student Outreach S. M. Bedair, North Carolina State University, DMR We currently have a new full-time international student, Mr. Zhenyu Liu, as well as Mr. Deonaire Bharrat, an underrepresented student from Guyana. Mr Bharat is currently supported by GRS supplemental funds from the NSF. During the 2013 Academic year, our group has welcomed two Chinese scientists, Xiuqin Chen and Xin Dong, in order to gain experience in our GaN lab. Dr. Chen learned and carried out magnetic measurement techniques such as alternating grade magnetometer (AGM) measurements. Dr. Dong interacted with our group in GaN growth and fabrication techniques in order to broaden his knowledge in these fields. (left) An alternating grade magnetometer (AGM) similar to the one used in our lab. It is used to measure spin-electronic GaN samples grown in the lab. (above) The metal organic chemical vapor deposition (MOCVD) system used in our lab. All of our samples are grown in the MOCVD.