Energy transfer and luminescence enhancement in Er-doped silicon

Er-doped silicon (Si:Er) is a promising light emitting material for silicon microphotonics. A study of Si:Er excitation/de-excitation mechanisms and luminescence enchancement is presented in this thesis. A model based on impurity Auger and nonradiative nmltiphonon transitions (NRl\·IPT) is shown to describe the temperature quenching of the photoluminescence (PL) intensity from 4K to 300K This model asserts that the nonradiative Auger process is mainly responsible for the temperature quenching below lOOK, and NRMPT backtransfer process is mainly responsible for the temperature quenching above lOOK. Junction photocufrei1t · spectmscopy (JPCS) measurements confirmed the existence of a backtransfer mechanism that grows with temperature in accordance to the model. In order to circumvent the onset of nonradiative transitions at higher temperatures, spontaneous emission enhancement in nrnltilayer Si/Si02 microcavities was explored as a means to increase the PL intensity. Because multilayer microcavity structures cannot be constructed using single crystal silicon, Er-doped polysilicon (poly-Si:Er) was developed as a light emitting material for these microcavities. The poly-Si:Er material exhibited a luminescence very similar to that of Er in single crystal silicon. By crystallizing poly-Si:Er from amorphous material and performing a post-anneal hydrogenation, a reasonably high PL intensity, which was limited by the excitation power, was attained. Microacavities with poly-Si:Er were fabricated and measured for the first time. Cavity quality factors of -60-300 were measured, and an Er enhancement of -20x was observed. A -lOx enhancement of a small background emission from the polysilicon was also observed. The observed enhancement factors match well with computed enhancement factors derived from electric field intensity distribution within the microcavity structure. Exploratory work in optical gain from Si:Er waveguides and vertically coupled ring resonntors was conducted. A fiber coupling technique for low temperature waveguide transmission experiments was developed for the gain experiments. The transmission spectrum of a 3-cm long waveguide was measured at temperatures down to 125K. Because the temperature could not be lowered without debonding the fiber, a net gain could not be observed in this particular waveguide. The application of stimulated emission in Si:Er devices is analyzed and discussed.

Department dc:contributor.department

Massachusetts Institute of Technology. Dept. of Materials Science and Engineering.

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

1999

Author dc:creator

• Chen, Thomas D. (Thomas Duhwa)

Advisor dc:contributor.advisor

• Lionel C. Kimerling.

• Materials Science and Engineering.

Statement dc:rights

• M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission.

Licence dc:rights.uri

• http://dspace.mit.edu/handle/1721.1/7582

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/1721.1/9536

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/9536