ATOMIC-SCALE STRUCTURAL AND LUMINESCENCE ENGINEERING OF INDIUM-RICH III-NITRIDE LIGHT-EMITTERS

Abstract

Heteroepitaxial III-nitride semiconductors integrated into silicon-based technology are among the most promising candidates for the next generation solid-state lighting/display sources. This stems from the fully tunable bandgap energy of the InGaN alloy, permitting complete control of the emission wavelengths across the entire visible spectrum. Yet, functional light-emitting diode devices suffer from poor efficiencies at longer wavelengths due to a diverse array of physical and compositional phenomena residing at the atomic level. This thesis takes an all-encompassing electron microscopy approach to decipher these localization centers responsible in various indium-rich designs. A variety of extended crystal defects (dislocations, stacking faults, and inversion domains), as well as quantum features (phase-separated precipitates and compositional fluctuations), were correlated with their distinct optical signatures. By understanding these intrinsic features governing the luminescence of In-rich InGaN light-emitters, new strain/defect engineering approaches for long wavelength emission were developed, giving rise to practical pathways towards fully solid-state lighting.