Epitaxial growth and characterization of hexagonal boron nitride for deep UV applications

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Hexagonal boron nitride has attracted a lot of interest in the deep UV community of late. Due to its wide bandgap (~ 6 eV), hBN has a significant potential for deep ultraviolet (DUV) photonic device applications. Additionally, the high neutron capture cross-section of the isotope boron-10 makes hBN a unique material for neutron detector applications. Its similar in-plane lattice constant to graphene and chemical inertness and resistance to oxidation makes hBN an ideal material for the exploration of Van der Waals heterostructures made layer by layer between hBN/graphene related materials with new physics and applications. This thesis work focuses on the development of high quality hexagonal boron nitride (hBN) by metal organic chemical vapor deposition (MOCVD). Growth of wafer scale hBN and the ability of electrical conductivity control in this exciting semiconductor are demonstrated. The structural and optical properties of hBN epilayers were characterized by X-ray diffraction and polarization resolved PL spectroscopy respectively. Micro-strip metal-semiconductor-metal detectors for thermal neutron sensing were fabricated and their performance was tested by continuous irradiation with a thermal neutron beam. Mg doped hBN epilayers were also grown on highly insulating AlN and n-type AlGaN templates with an attempt to demonstrate hBN/AlGaN p-n junctions. The current-voltage (I-V) characteristics of hBN/6H-SiC heterostructures were measured and the results were utilized to determine the band offsets of the hBN/6H-SiC heterojunctions. Electrical transport measurements of Silicon doped hBN epilayers were carried out to investigate the suitability of Si as an n-type dopant in hexagonal boron nitride.

Photonics, Hexagonal boron nitride (hBN)