The characteristics of electrically injected silicon-based photonic crystal microcavities with PbSe quantum dots are described. The device includes suitable electron and hole transporting layers and contact layers. The measured electroluminescence at room temperature exhibits an enhanced spontaneous emission. The resonant mode is observed at lambda=1669 nm with a spectral linewidth of 4 nm, corresponding to a cavity Q factor of approximately 420.
[Show abstract][Hide abstract] ABSTRACT: The most significant accomplishments in this project are: (a) the demonstration of optically pumped silicon based light emitters utilizing colloidal PbSe QD which are inserted in PC microcavities for efficient coupling. Enhancements of spontaneous emission with a linewidth of-2.0 run, corresponding to a cavity Q factor of 775, is observed at 1550 nm at room temperature; (b) an electrically injected silicon based light source using PbSe QDs, which are more compact and versatile. With a current density of 113 mA/cm2, a resonance at X=1669 nm having a linewidth of 4nm is observed, which corresponds to a cavity Q factor of-420. This nanoscale light source based on silicon, which is capable of being fabricated on CMOS chips, is of interest as a practical technology for optical interconnects in silicon photonics; (c) the demonstration of possibility of surface Plasmon enabled nanolaser with round-trip gain in the sense that the transmission in the waveguide increases as the pumping power increases.
[Show abstract][Hide abstract] ABSTRACT: Coherent and directional emission at 1.55 μm from a PbSe colloidal quantum dot electroluminescent device on silicon is demonstrated. The quantum dots are sandwiched between a metallic mirror and a distributed Bragg reflector and are chemically treated in order to increase the electronic coupling. Electrons and holes are injected through ZnO nanocrystals and indium tin oxide, respectively. The measured electroluminescence exhibits a minimum linewidth of ~3.1 nm corresponding to a cavity quality factor of ~500 at a low injection current density of 3 A/cm2, and highly directional emission characteristics.
[Show abstract][Hide abstract] ABSTRACT: We report coupling of the excitonic photon emission from photoexcited PbSe colloidal quantum dots (QDs) into an optical circuit that was fabricated in a silicon-on-insulator wafer using a CMOS-compatible process. The coupling between excitons and sub-μm sized silicon channel waveguides was mediated by a photonic crystal microcavity. The intensity of the coupled light saturates rapidly with the optical excitation power. The saturation behaviour was quantitatively studied using an isolated photonic crystal cavity with PbSe QDs site-selectively located at the cavity mode antinode position. Saturation occurs when a few μW of continuous wave HeNe pump power excites the QDs with a Gaussian spot size of 2 μm. By comparing the results with a master equation analysis that rigorously accounts for the complex dielectric environment of the QD excitons, the saturation is attributed to ground state depletion due to a non-radiative exciton decay channel with a trap state lifetime ~ 3 μs.
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