Reduction in compressive stress in GaN with increasing trimethylindium flow rate

1. r h a Effect of Indium on Compressive Stress Relaxation in GaNJoan Redwing, Pennsylvania State Univ University Park, DMR 0606451 Indium acts as a surfactant on GaN resulting in a change in the relative surface energies which drives the formation of undesired V-pit defects. Strain energy also plays a role in V-pit formation but is not as well understood. The addition of indium was found to relax compressive stress in GaN grown by MOCVD as measured by in-situ curvature measurements. The stress relaxation was correlated to an increase in the size and density of V-pit defects. The change in system energy was calculated and was used to investigate the effects of indium, film strain and dislocation density on the driving force for V-pit formation. The model predicts a reduction in V-pit density when the film strain is reduced which has implications for the growth of InGaN layers for optoelectronic applications. Reduction in compressive stress in GaN with increasing trimethylindium flow rate TMIn=0 sccm TMIn=4.5 sccm Energy barrier for V-pit formation

2. Outreach to Middle School/High School StudentsJoan Redwing, Penn State University, DMR 0606451 The PI participated in a mentoring program for middle school/high school girls. The program is designed to stimulate interest in science and technology via the development of personal relationships with women faculty at Penn State. Over the past year, the PI organized two mentoring program activities including a hands-on workshop on fiber testing and a field trip to the Corning Museum of Glass. Partial financial support for this program was provided by the NSF through this grant, a NIRT grant and the Penn State MRSEC Center for Nanoscale Science. Mentor program participants carrying out fiber combustion tests. Examining fibers under the microscope.