* Refreshments will be served at 3:30 PM in the Lower Level 1 Gossage Atrium
* Lecture commences at 4:00 PM in L1255 in the Ford ES&T Building

Seminar Abstract
GaAs-based multiple quantum well heterostructures comprised of metastable alloys, such as
GaAs1-ySby - GaAs1-zNz, have been recently studied due to their projected broad applications.
These materials have potential for realizing high-performance, reduced temperature-sensitivity
lasers in the 1.55 μm wavelength region for telecommunications as well as much longer
wavelengths useful in sensing applications. These materials are also interesting since they exhibit extensive miscibility gaps which can prevent the formation of a homogenous alloy over the
entire range of desired material compositions. The interaction of strain, surface segregation and
defect formation energies can alter this range of miscibility. Additionally, specific changes in the
growth chemistry of these materials can interact with these physical and thermodynamic factors
to alter the achievable alloy compositions and enable new device applications. The chemical
formation through vapor phase processes of such materials and their device applications will be
presented. The impact of surface chemistry on the alloy composition will be discussed along
with extensions to other important materials systems.