Electrical and Computer Engineering ETDs

Publication Date



Alxln(1-x)AsySb(1-y)quaternary alloys have been used in Type I midwave infrared (MWIR) laser structures as barrier materials with lnAs and InAsSb quantum wells. However, growth of these alJoys has limited the application because of a large miscibi lity gap. In this research, quaternary films with compositions well into the miscibility gap (0

Combining the quaternary bandgap equation with strain and quantum size effects. the wavelengths for strained lnAsSb wells in AllnAsSb quaternary barriers are predicted and compared to measured values generated from PL experiments. The reasonable agreement of these experimental results with the theoretical model supports the assertion that the AIInAsSb/lnAsSb material system is Type I and emits in the target wavelength range of 3.3-4.2 μm. PL spectra of AllnAsSb/InAsSb multiple quantum weJls exhibit a substantial increase in intensity with increasing quaternary aluminum content. This is presumably due to increasing valence band offset and, therefore, to better hole confinement. A laser with this active region has been fabricated and tested. Under pulsed optical pumping conditions at 50K, the laser emitted light at -3.93 μm.

Further work has been done using the digital alloy technique to add gallium to the quaternary alloy to produce an AlGalnAsSb quinary alloy lattice-matched to GaSb. This material is of specific interest for mid-infrared lasers because by adding the fifth element, gallium, the range of material properties is extended. There is some indication from PL testing that the addition of the fifth element may contribute to Auger recombination suppression and may lead to higher operating temperatures. DCXRD and TEM of these quinary alloys give results similar to the quaternary alloys. The stable, single-phase growth of these quinary alloys shows promise for improving the performance of MWIR lasers.

Document Type




Degree Name

Electrical Engineering

Level of Degree


Department Name

Electrical and Computer Engineering

First Committee Member (Chair)

Luke F. Lester

Second Committee Member

L. Ralph Dawson

Third Committee Member


Third Advisor

Kevin J. Malloy