This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).
This project seeks to solve two key issues of InGaN materials. First, how do lattice strain, composition, internal polarization fields, surface polarity, defect, and dopant incorporation influence p-type conductivity in InGaN? Second, what is the cause of the intrinsic surface electron layer in InN? This layer obscures the bulk free charge carrier properties in contact-based electrical measurements, in the extreme case concealing p-type conductivity. The experimental approach of this project comprises InGaN thin film analysis with variation of spontaneous and piezoelectric fields, surface orientation, composition, surface defects, and dopant incorporation. It employs a newly developed optical Hall-effect technique, which permits noncontact, noninvasive charge carrier profiling and tackles the present challenges in p-conductivity research on InGaN. The success of the project may also open a door to answer the open questions about the surface charges in InAs.
The project addresses basic research issues in a topical area of materials science with high technological relevance. The success of the project is expected to have impacts on the further advancement of optoelectronics, solid state lighting, and solar cells. The project provides training of graduate and postdoctoral students. The PI and his students participate in education outreach activities for solar energy use in remote areas of Nebraska. The PI is also active in the professional societies and organizes several symposia on ellipsometry in scientific conferences.
