Fabrication and characterization of electrically injected photonic crystal light emitters

Electrically injected photonic crystal light emitters with spatially localized gain are explored with the goal of understanding the optical and electrical characteristics of these devices from theoretical and experimental perspectives. Localization of the quantum well layer into the defect region of the photonic crystal allows for efficient coupling of the optical mode to the gain medium and reduces non-radiative recombination at the semiconductor air interfaces formed by the photonic crystal air holes. The use of a submicron diameter oxide aperture enables optical and electrical confinement. The design parameters of the photonic crystal nanocavity structure are determined by computing the photonic band gap and cavity resonant modes. Secondary ion mass spectrometry analysis is used to assist the development of an epitaxial structure in the InGaAs/GaAs material system for electrical injection. The challenging fabrication procedure demands stringent process control and high resolution lithography technology including electron beam lithography or focused ion beam nano-patterning. Electroluminescence spectra at room temperature demonstrate the effect of the photonic crystal nanocavity. Significant enhancement of the electroluminescence intensity is observed as a result of the spatial localization of the quantum well to the photonic crystal defect. The measured spectra of photonic crystals with different periods compare favorably to the theoretical model. In summary, advanced nanofabrication techniques in conjunction with advanced semiconductor growth technology have been used to fabricate electrically injected photonic crystal light emitters in the InGaAs/GaAs material system, and avoid the problems associated with non-radiative surface recombination.