Global Strain-Free III-Nitride Heterostructures: Growth, Structure and Near-Infrared Optical Properties

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AbstractTechnical description: The main objective of this project is to establish the relationship between growth, atomic structure and optical properties of lattice-matched and strain-balanced AlInN/(In)GaN multi-quantum well structures. In order to correlate the growth modes with microstructure and near-infrared optical properties, AlInN/(In)GaN heterostructures are grown by plasma-assisted Molecular Beam Epitaxy (MBE) on extremely high quality quasi-bulk GaN substrates, the atomic structure of the semiconductor materials is characterized in detail using high-resolution x-ray diffraction and transmission electron microscopy, while the near-infrared optical properties of the materials are examined experimentally using Fourier transform infrared spectroscopy. This project advances the understanding of MBE growth of strain-free III-nitride materials for complex infrared optoelectronic devices. Basic mechanisms of material growth such as adatom kinetics and impurity incorporation on polar and non-polar GaN substrates are studied in detail and compared. The goal is to achieve adequate understanding and control of the growth process, resulting microstructure and infrared optical properties in order to realize the theoretical potential of this material system. The fundamental and practical limitations for MBE growth, in particular for metal-modulated epitaxy, of complex nitride heterostructures are established. Non-technical description: This project investigates a new class of semiconductor materials for infrared light sources and detectors that has the potential to enable new practical applications (infrared spectroscopy, infrared imaging, and telecommunications) with broad benefits to society. This research also increases the learning opportunities for students of all ages, inside and outside the traditional classroom by integrating interdisciplinary research with broader physics and engineering education and training. In particular, the students involved in this project have the opportunity to acquire hands-on experience with the latest materials fabrication and characterization tools and techniques. The excitement of scientific discovery is conveyed to students through collaborations with several research groups in academia, industry, and national laboratories. The interaction with scientists in industry and a federally funded laboratory offers the students a different view of the scientific pursuit, as well as a better understanding of their career options. The PIs and students also will participate in outreach activities organized either in-house or at local schools to increase exposure of K-12 students and the general public to modern scientific topics at the border between physics, material science, and engineering through Purdue?s highly popular Physics on the Road Project.