Optical Emission from Single-Crystal Silicon

The thought of merging integrated optics and electronics on a silicon medium is a very attractive idea because it is easy to imagine building upon the already established electronics industry. In general, integrated optical devices are not constructed from silicon because some of its inherent properties are not conducive to certain needs of integrated optics. A medium that can act as a light source as well as a waveguide would meet two of the more important needs. The problem with silicon is that it has an indirect band-gap and this prevents it from being an intrinsic light emitter except at very low temperatures. One method of overcoming this obstacle is with impurities that create energy levels in the band-gap where radiative transitions can occur. Isoeletronic centers are one type of impurity complex that do this, and four isoelectronic complexes, including a newly discovered one, are studied in this thesis. Both photo- and electroluminescence (PL & EL) experiments were performed as well as measurements to determine radiative lifetimes, external quantum efficiencies, thermal properties of the luminescence, chemical make-up of a center, and optimization of annealing procedures used to create the Be-related isoelectronic impurity. Specifically, an investigation of the dependence of the sulfur-related PL on the concentration of sulfur is presented. Concentration quenching of the sulfur-related PL is observed and new conclusions about the chemical make -up of the sulfur-related complex are discussed. The newly discovered selenium-related complex that exhibits luminescence at temperatures greater than 80 K is characterized and the striking similarities between it and sulfur suggests that they are closely related. The belief that other chalcogens will not display similar behavior is also presented. Further, it is shown that these centers can act as sources in waveguide structures, being excited either optically or electrically, and a silicon LED (in a waveguide structure) with 0.2-0.5% efficiency at T cong 60 K is demonstrated. Also, evidence that oxygen plays a significant role in the indium -related complex is presented.