GaN-Based Vertical Cavity Surface Emitting Lasers and Resonant Cavity Light Emitting Diodes

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ECCS- 0725506Morkoc, HadisVirginia Commonwealth UniversityIntellectual MeritsBrighter and higher efficiency light sources possibly based on vertical cavity technology are imperative for fully successful solid-state lighting and telecommunications. The proposed research employs novel epitaxial film growth/fabrication techniques for high quantum efficiency GaN-based microcavity light emitting diodes and electrically injected vertical cavity surface emitting lasers in the violet-green spectral region. Short wavelength GaN-based vertical cavity lasers will very likely provide the foundation for high-density optical data storage and high-speed optical communication, and lighting. The incoherent microcavity emitters also surpass their conventional counterparts due to their directionality, spectral purity, and increased photon extraction efficiency, making them ideal for solid-state lighting with high color rendering index and displays. Both in situ and ex situ epitaxial lateral overgrowth techniques will be used to reduce defect densities in the GaN material. Vertical cavity structures will be fabricated on the nearly defect-free wing regions of the laterally overgrown GaN to avoid nonradiative centers caused by extended and point defects. A unique epitaxial lateral overgrowth technique will allow the bottom metal and/or dielectric reflector stacks, to be used also as the growth masks. By introducing a second lateral overgrowth step, the current conduction will be allowed only through the defect-free active region of the device, promoting efficient hole injection.Broader ImpactsThe proposed research can potentially produce high brightness light sources for general lighting with energy savings and reduced carbon footprint, displays, and vertical lasers for optical storage/networks. Because, the demand for optical storage is growing, development of densely integrated blue vertical cavity lasers can meet the need for faster read-out and writing. Considering the novelty of the proposed device structures intense industrial collaborations are anticipated. This proposal will provide the students and interns with opportunities for cross-disciplinary learning, interactions with international scientists in the group and elsewhere, development of industrial networking, and for realization of the impact of new technologies on the marketplace and environment.