SGER: An Investigation of Silicon Germanium Terahertz Sources

University Of Delaware, Newark DE

Investigators

Abstract

Layers of boron doped and gallium doped Si and SiGe will be grown by molecular beam epitaxy on Si substrates. Device structures will be fabricated using photolithography combined with reactive ion etching and metal evaporation. Their electroluminescent properties will be determined as a function of dopant type and concentration. Electrical and optical device modeling will be used to help interpret the observations. Electroluminescence measurements will be made on electrically contacted devices mounted in a cryostat in a Fourier Transform Infrared Spectrometer that operates in the THz range. In particular, the emission intensity and spectrum will be determined versus the applied current and temperature. Based on the results, the possibility of designing a TeraHertz laser based on dopant transitions will be assessed in terms of the radiative gain and losses from doped cavity resonators. The proposed research should be considered exploratory and high risk because the excitation mechanism of the dopant states and their radiative efficiency is not well understood, and will be explored during this project. The potential impact of this research concerns a TeraHertz emitting device with a simple structure that is compatible with Si integrated circuitry for potential low cost and widespread use. Compact TeraHertz emitters that are integrated with computer chips would have applications in: chemical and biological sensing; medical diagnostics, and high bandwidth communications. An SGER grant would be a suitable means of supporting the work because the results would indicate whether additional research is justified, and may be used to solicit additional funding. Education and outreach activities will be carried out in combination with these research activities. These will include the participation in research of a graduate student, the incorporation of research findings into teaching, and the continued development of a series of local school outreach activities. An interactive web site (http://www.ece.udel.edu/~kolodzey/terahertztools/terahertztools.htm) will be designed suitable for senior high school or freshman college students, which will illustrate the properties of the TeraHertz frequencies, and allow students to explore terahertz absorption and reflectivity phenomena.