Surface morphology of N-polar GaN grown without (top) and with (bottom) indium

1. Influence of Surfactants on the Growth of N-polar GaNJoan M. Redwing, Penn State University, DMR 1006763 Heteroepitaxial growth of GaN can occur along either the [0001] (Ga-polar) or the [0001] (N-polar) direction. While the majority of GaN-based devices are Ga-polar, there is growing interest in N-polar growth as a route to fabricate novel structures. It has proven challenging, however, to grow N-polar GaN by metalorganic chemical vapor deposition due to the formation of hexagonal hillocks which degrade the surface morphology. Previous studies have demonstrated that the density of hillocks on N-polar GaN can be reduced through the use of miscut substrates, although macrosteps are still commonly observed. In this study, we demonstrate that the addition of indium surfactants during GaN growth alters step-edge surface energies leading to a significant reduction in the surface roughness of N-polar GaN. Surface morphology of N-polar GaN grown without (top) and with (bottom) indium (scan size 20 x 20 mm)

2. Development of LED-related Activities for an Interactive Demonstration Kit on Energy Materials Joan M. Redwing, Penn State University, DMR 1006763 We are working with the Franklin Institute Museum in Philadelphia, PA and members of the Penn State MRSEC Center for Nanoscale Science on the development of light emitting diode (LED)-related activities for a cart-based, interactive demonstration kit on energy materials. Over the past year, graduate students supported by the current project met with museum personnel to provide technical input on the demonstration activities and advice on how to handle LED-related questions. During the coming year, the graduate students will be trained to demonstrate the cart-based activities for outreach programs at Penn State. Graduate students Dongjin Won (left) and Jarod Gagnon (right) meeting with Franklin Institute staff members.