Scanning tunneling microscopy of III-V semiconductors
Skala, Stephen Lawrence
This item is only available for download by members of the University of Illinois community. Students, faculty, and staff at the U of I may log in with your NetID and password to view the item. If you are trying to access an Illinois-restricted dissertation or thesis, you can request a copy through your library's Inter-Library Loan office or purchase a copy directly from ProQuest.
Permalink
https://hdl.handle.net/2142/20570
Description
Title
Scanning tunneling microscopy of III-V semiconductors
Author(s)
Skala, Stephen Lawrence
Issue Date
1994
Doctoral Committee Chair(s)
Lyding, Joseph W.
Department of Study
Electrical and Computer Engineering
Discipline
Electrical Engineering
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
Physics, Condensed Matter
Engineering, Materials Science
Language
eng
Abstract
Scanning tunneling microscopy (STM) has been used to study the (100) surface of GaAs and the (110) plane of cross-sectioned GaAs/AlGaAs heterolayers. Observation of the GaAs(100) surface with STM has characterized the c(8x2) reconstruction and shows that the c(8x2) consists of ordered (4x2) subunits. Each (4x2) subunit contains two As and two Ga dimers, contrary to previous descriptions which include only Ga dimers. This model of the c(8x2) reconstruction also agrees well with results from other experimental techniques. The (2x6) reconstruction is observed to be considerably more complex than the c(8x2) and bears little resemblance to either the c(2x8) or c(8x2) reconstructions.
STM investigations on vicinal GaAs(100) substrates have clearly shown that steps migrate to form arrays of terraces $\sim$175 A wide separated by regions of bunched steps on 2$\sp{\rm o}$ toward (110) oriented substrates after annealing to a temperature high enough to form a mixed c(8x2) and (2x6) reconstruction. The coexistence of the two reconstructions is critical to step bunching as the c(8x2) is observed to occupy only the terraces while the (2x6) exists predominately across the steps. Bunched step arrays are not observed on 2$\sp{\rm o}$ toward (110) oriented substrates, and a considerably higher ratio of (2x6) reconstructions is present on these substrates than on the 2$\sp{\rm o}$ toward (110) oriented substrates.
STM results on cross-sectioned GaAs/AlGaAs heterolayers show differences in current contrast between p- and n-type layers which can be explained by band bending caused by charged oxygen adsorbates on AlGaAs.
Use this login method if you
don't
have an
@illinois.edu
email address.
(Oops, I do have one)
IDEALS migrated to a new platform on June 23, 2022. If you created
your account prior to this date, you will have to reset your password
using the forgot-password link below.
