Investigation of high In-composition InGaN

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Abstract:Technical: High In-composition alloys (InGaN, xIn 0.25) are among the most unexplored materials in the III-nitride system. While the bandgap range of InGaN alloys can cover the entire spectrum from ultra-violet (Eg, GaN ~ 3.4 eV) to infrared (Eg, InN ~ 0.7 eV), technological applications until now are restricted to the higher energy range of this spectrum. The relatively low number of applications in the lower bandgap III-nitride alloys is due to the challenges associated with epitaxial growth, and poor understanding of the electrical, defect, and optical characteristics of these materials. This project will address the critical issues relating growth and structural properties to electrical, optical, and defect properties to achieve higher composition InGaN films on N-polar orientation of GaN. This project will investigate the growth kinetics for this material in metal-rich and nitrogen-rich regimes to create a comprehensive growth model for Ga- and N-polar InGaN. This study will include thick InGaN films and strained InGaN films on GaN to understand the physical origins of phase segragation, dislocation-mediated relaxation, and surface morphologies. Electrical and optical characterizations of the films will lead to an understanding of p-type and n-type doping, as well as the background defect incorporation in the films (through deep level optical spectroscopy). Non-Technical: The study will enable device applications that exploit the large bandgap range of III-nitrides. Extending the tremendous commercial success of III-nitride emitters to a larger range of optical and electronic applications will be transformative to the semiconductor technology industry. The PIs have a strong record of extending their research activities to involve high school students. The interdisciplinary nature of this project requires close collaboration between the different groups involved, and will be excellent training for undergraduate and graduate students involved.