Development of SiGe-based Quantum Well Laser Diodes

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The chief objective is to pave the way for the realization of an inverted population in an attempt to generate stimulated emissions in SiGe-based indirect-gap quantum wells by exploiting the state-of-the-art epitaxy and advanced quantum electronics.To this end, much efforts were directed toward the epitaxial cavity formation to control the spontaneous emission. Highly-reflective Si/Sio_2 Bragg mirrors and a one-wavelength well-centered microcavity were fairly successful. A infrared-enhanced photomultiplier allowed the observation of a luminescence lifetime difference between edge- and surface-emissions.Apart from cavity-based manipulation, a total suppression of phonon-aided spectra was demonstrated using interface-engineering. Three-dimensional Ge islands were used as quantum dots to break the translational symmetry thereby removing the otherwise strict momentum conservation. Prolonged radiative lifetimes were in support of a k-diagonal radiative recombination as expected.As to indire … More ct-exciton recombinations, much was newly found ; A large anisotropy for the edge emissions, the missing light-cone limitations on thermalization, a large Coulomb screening, an enhanced band-gap renormalization, a lifetime reduction due to 2-D confinement, the masked quantum-confined Stark effects, and etc.For comparative purposes, the zone-folded superlattice was revisited in an attempt to rectify misleading concepts. Significance of structural disorders which would intimidate the predicted luminescence properties was pointed out. An ordered short-period superlattice was found to be inevitably transformed into a disordered one due to a large inhomogeneous witdth and a narrow miniband of the ground state.From technical standpoint, device characteristics were also atudied. Dynamical backscattering was observed for a quantum-well potential. A virtual blocking was confirmed by monitoring time-reolved spectra. Furthermore, the Si-SiO_2 technique was extended for the fabrication of orderly Si dots for use as light emitters replacing SiGe quantum wells. Less