Optical constants and origin of the absorption edge of GaPN lattice-matched to Si
| Autor: | Stefan Krischok, Thomas Hannappel, Christian Koppka, S. Shokhovets, Oliver Supplie |
|---|---|
| Rok vydání: | 2018 |
| Předmět: |
Physics
business.industry 02 engineering and technology 021001 nanoscience & nanotechnology Thermal conduction Epitaxy 01 natural sciences Redshift Condensed Matter::Materials Science Semiconductor Absorption edge Lattice (order) 0103 physical sciences Direct and indirect band gaps Atomic physics 010306 general physics 0210 nano-technology Rotational–vibrational coupling business |
| Zdroj: | Physical Review B. 98 |
| ISSN: | 2469-9969 2469-9950 |
| Popis: | We report the room-temperature dielectric function (DF) of GaPN grown lattice-matched on Si(100). Data were derived from spectroscopic ellipsometry measurements on a series of films prepared by metalorganic vapor phase epitaxy. The Kramers-Kronig analysis reveals good self-consistency between the real and the imaginary parts of the determined DF. The onset of a strong absorption in GaPN is clearly redshifted with respect to the direct band gap of GaP. In contrast, direct optical transitions at the ${E}_{0}$ and ${E}_{1}$ critical points (CPs) in GaPN are remarkably blueshifted. The experimental data near the absorption edge are analyzed using the k \ifmmode\cdot\else\textperiodcentered\fi{} p model of the valence-band structure and the experimentally motivated band anticrossing model to describe the conduction band. We found that the resulting Kane's matrix element for the lower conduction subband is quite small (${E}_{\mathrm{P},\ensuremath{-}}=0.64\phantom{\rule{0.16em}{0ex}}\mathrm{eV}$), which indicates a relatively low probability of the respective direct optical transitions compared to typical direct band-gap semiconductors, such as GaAs, InP, or GaN. In addition, a considerable contribution of phonon-assisted optical absorption processes occurs. These observations are interpreted in terms of quasilocalization of nitrogen-induced electronic states responsible for optical transitions below the ${E}_{0}$ CP and their significant vibrational coupling to the lattice. |
| Databáze: | OpenAIRE |
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