Event Details
Ellipsometry measurements of the optical properties of GaAs1-xBix alloys
Presenter: Mahsa Mahtab
Supervisor:
Date: Wed, January 23, 2019
Time: 15:00:00 - 16:00:00
Place: EOW 230
ABSTRACT
Abstract:
Silicon and III-V semiconductor devices are ubiquitous in computing and communication systems. There is a need for new semiconductor materials with more favorable properties for long wavelength lasers and imaging systems and for terahertz devices. The III-V semiconductor alloys containing Bi are a new class of long wavelength semiconductor materials that may be suitable for these applications.
Incorporation of up to 17% Bi into GaAs reduces the band gap from 1.4 eV to 0.6 eV and enables longer wavelength devices to be fabricated on GaAs substrates with a comparatively small lattice mismatch.
Spectroscopic ellipsometry is a well-known non-destructive optical method to measure thin film properties like thickness and optical constants with high accuracy. In this presentation, the complex dielectric constants of GaAs1-xBix alloys grown by molecular beam epitaxy have been studied by ellipsometry. The band gap and other optical features of GaAs1-xBix alloys are discussed over the spectral range from 0.37-9.0 eV. The energy of the critical points is discussed and dependence on Bi concentration is investigated.