Si-Based Photonic Devices by MBE

Abstract

ABSTRACTThe prospect of efficient electroluminescence and photodetection in Si-based heterostructures has stimulated considerable interest in recent years. Si-based optoelectronic devices would allow monolithic integration of mature Si technology with optical signal processing. However, Si and epitaxial Si1−xGex/Si (100) alloys are indirect semiconductors and band structure perturbations are necessary to enhance luminescence efficiencies to practical levels. In this review we consider the relative success of the various approaches used to obtain efficient luminescence from Si based heterostructures after first considering the optical properties of Si grown by MBE and doped by several techniques. Exciton binding centers such as isoelectronic defect complexes, zone folding in atomic layer superlattices, e.g. SimGen, and rare earth doping, e.g. Er in Si and Si1−xGex alloys are discussed. The internal quantum efficiencies for the above processes will be compared in both electroluminescence and photoluminescence together with the prospects for room temperature light emission. The twin requirements of band structure engineering and superlative crystal quality extend the challenge to the materials scientist / crystal grower further into the nanoscopic regime. It is a formidable task involving the controlled removal of non-radiative point defects and complexes, controlled introduction of radiative centers, and simultaneous maintenance of coherent interfaces without misfit dislocation injection. Recent progress in our study of intense photoluminescence (wavelength range 1.2 -1.7 μm) from random Si1−xGex alloys (0.53 > × > 0.06) grown by MBE, a 1.5 μm Si0.82Ge0.18/Si LED and a novel Si1−xGex/Si optoelectronic switch will be highlighted.