Systematic study of Ge1−xSnx absorption coefficient and refractive index for the device applications of Si-based optoelectronics
Abstract
The absorption coefficient and refractive index of Ge1−xSnx alloys (x from 0% to 10%) were characterized for the wavelength range from 1500 to 2500 nm via spectroscopic ellipsometry at room temperature. By applying physical models to fit the obtained data, two empirical formulae with extracted constants and coefficients were developed: (1) Absorption coefficient. The absorption regarding Urbach tail, indirect and direct bandgap transitions were comprehensively taken into account; (2) refractive index. The Sellmeier coefficients associated with dispersion relationship were extracted. In these formulae, the Sn composition and strain percentage were the input parameters, by inputting which the spectral absorption coefficient and spectral refractive index can be obtained. Since the absorption coefficient is key information to determine the performance of the photodetectors including operation wavelength range, responsivity, and specific detectivity, and the refractive index is very useful for the design of the anti-reflection coating for photodetectors and the layer structure for waveguides, the developed formulae could simplify the optoelectronic device design process due to their parameter-based expressions.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- Mar 11, 2016
- Source ID
- 10.1063/1.4943652
Entities
People
- Aboozar Mosleh
- Baohua Li
- Greg Sun
- Hameed A. Naseem
- Huong Q Tran
- Joe Margetis
- John Tolle
- Richard Soref
- Seyed Amir Ghetmiri
- Shui-Qing Yu
- Wei Du
Organizations
- Air Force Office of Scientific Research
- Air Force Research Laboratory
- Defense Advanced Research Projects Agency
- National Science Foundation
- University of Arkansas
- University of Massachusetts Boston