Details

Phonon-assisted tunneling in silicon/silicon-germanium resonant interband tunnel diodes

by 1972- Yu, Ronghua

Abstract (Summary)
Electron tunneling spectroscopy was applied toward Si/SiGe resonant interband tunnel diodes (RITDs) to ascertain the phonon spectra of the composite tunneling barrier which consists of Si1?xGex and Si layering. Two issues were identified: the error in the second-order derivative which would reduce the measurement sensitivity, and the contact resistance which would affect phonon energy measurement. A harmonic detection system was used to measure the first-order derivative with an accuracy of 10?4, followed by first-order numerical differentiation to obtain high quality second-order derivative. Contacts to silicon using nickel silicide (NiSi) and delta doping technique were studied, and preliminary results indicate that the contact resistance was very low. With typical Si/SiGe RITD configurations, the phonon spectra were found to be dominated by the phonon peaks of bulk Si. Of the Si/SiGe RITD structures that were measured, only those with a relatively thick Si1?xGex layer in the composite tunneling barrier and a high Ge content x = 0.6 produced phonon spectra in which the transverse acoustic (TA) phonon of the Si0.4Ge0.6 were observable, but the longitudinal acoustic (LA), longitudinal optical (LO) and transverse optical (TO) phonons of Si1?xGex were not observed. The energy of the TA phonon of Si0.4Ge0.6 in Si/SiGe RITDs grown on Si substrates was determined to be about 4±1 meV higher than that measured using Esaki tunnel diodes. This increase is attributed to the compressive strain in the Si0.4Ge0.6 layer in the Si/SiGe RITDs. iv VITA March 23, 1973 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Born - Shuangliu, Sichuan, P.R. China 1994 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .B.S. Physics, University of Electronic Science and Technology of China, Chengdu, Sichuan, P.R. China 1997 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .M.S. Physics, University of Science and Technology of China, Hefei, Anhui, P.R. China 1999 - present . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Graduate Fellowship, Graduate Research Associate, Graduate Teaching Associate, The Ohio State University, Columbus, OH, U.S.A.
Bibliographical Information:

Advisor:

School:The Ohio State University

School Location:USA - Ohio

Source Type:Master's Thesis

Keywords:phonons tunnel diodes silicon alloys germanium

ISBN:

Date of Publication:

© 2009 OpenThesis.org. All Rights Reserved.