Surface reconstructions of In-enriched InGaAs alloys

The atomic structure of In0.81Ga0.19As/InPIn0.81Ga0.19As/InP alloy layers was examined using in situ scanning tunneling microscopy. The (2×3) reconstruction observed during growth by reflection high-energy electron diffraction represents a combination of surface structures, including a β2(2×4) commonly observed on GaAs(001) and InAs(001) surfaces, and a disordered (4×3) that is unique to alloy systems. The proposed (4×3) structure is comprised of both anion and cation dimers. Empty and filled states images show that the features reverse contrast with sample bias, in agreement with the model. © 2003 American Institute of Physics.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/70065/2/APPLAB-83-7-1361-1.pd

Photoluminescence Studies of Lateral Composition Modulated Short-Period AlAs/InAs Superlattices

We present low temperature photoluminescence data for a series of spontaneous lateral composition modulation in (AlAs){sub m}/(InAs){sub n} short period superlattices on InP with differing average lattice constants, i.e., varying global strain. The low temperature photoluminescence peak energies were found to be much lower than the corresponding energy expected for the equivalent In{sub x}Al{sub 1{minus}x}As alloy. The bandgap energy reductions are found to approach 500 meV and this reduction is found to correlated with the strength of the composition modulation wave amplitude

The role of college knowledge and proactive behavior on participation in cocurricular activities

BackgroundDemographic characteristics are known to influence participation in cocurricular activities. Less studied are the effects of other background characteristics.PurposeWe hypothesize that considering college knowledge and students’ proactive behaviors in tandem with demographics provides better models for predicting such participation.MethodWe developed a questionnaire and administered it to 3,618 domestic third- and fourth- year undergraduate engineering students at a large public R1 Midwestern university, yielding 860 responses. Logistic regression models predicting five types of cocurricular participation were constructed with demographic characteristics, college knowledge, and proactive behaviors in all combinations as predictors.ResultsFour of five types of cocurricular participation were better modeled using factors beyond demographics. Two were better modeled using only proactive behavior as predictors and two were better modeled using demographics in combination with either college knowledge or proactive behavior. Only one type of participation could be best predicted by demographics alone.ConclusionsThese findings contribute quantitative evidence establishing relationships between participation in engineering cocurricular activities and a wider range of factors than previously reported. Furthermore, they provide guidance for creating intervention programs because, unlike demographics, college knowledge and proactive behavior can be shaped by either the individual or the institution.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/166390/1/jee20380.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/166390/2/jee20380_am.pd

<title>Detection of lateral composition modulation in an (InAs)n/(GaAs)n short-period superlattice on InP by magnetoexciton spectroscopy</title>

An experimental signature for detecting spontaneous lateral composition modulation in a (InAs){sub n}/(GaAs){sub n} short period superlattice on a InP substrate based on magnetoexciton spectroscopy is presented. The authors find by aligning the magnetic field in three crystallographic directions, one parallel to and the other two perpendicular to the composition modulation direction, that the magnetoexciton shifts are anisotropic and are a good indicator for the presence of composition modulation

Detection of lateral composition modulation in a (InAs){sub n}/(GaAs){sub n} short period superlattice on InP by magnetoexciton spectroscopy

An experimental signature for detecting spontaneous lateral composition modulation in a (InAs){sub n}/(GaAs){sub n} short period superlattice on a InP substrate based on magnetoexciton spectroscopy is presented. The authors find by aligning the magnetic field in three crystallographic directions, one parallel to and the other two perpendicular to the composition modulation direction, that the magnetoexciton shifts are anisotropic and are a good indicator for the presence of composition modulation