Regensburg 2019 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 36: II-VI- and III-V-semiconductors
HL 36.6: Vortrag
Donnerstag, 4. April 2019, 11:00–11:15, H31
XPS and Disorder Analysis of Quaternary Ga1-xInxAs1-yBiy Semiconductor Alloys — •Julian Veletas1, Thilo Hepp2, Kerstin Volz2, and Sangam Chatterjee1 — 1Institute of Experimental Physics I and Center for Materials Research, Justus-Liebig-University Giessen, D-35392 Giessen — 2Faculty of Physics and Materials Sciences Center, Philipps-Universität Marburg, D-35032 Marburg
The incorporation of small fractions of bismuth atoms in III-V semiconductors such as Ga1-xInxAs1-yBiy leads to a decrease of the band gap energies and increase of the spin-orbit splitting energies of the alloy. This is attributed to an anti-crossing between the Bi-level with the valence bands of the matrix. Eventually the band gap energies may even get smaller than the spin-orbit splitting energy beyond certain fractions of bismuth incorporation into Ga1-xInxAs1-yBiy alloys. This is expected to lead to a suppression of non-radiative Auger recombination. However, growth of such materials remains challenging due to the required low growth temperatures. Furthermore, characterization is challenging due to similar influences of In and Bi incorporation on major electronic and structural properties, such as the band gap energy and the lattice constant.
In this study, we complement standard characterization techniques with XPS. We show the influence of different partial pressures of the MOVPE growth on the bismuth segregation process as well, as on the alloy elemental composition. Using the VBAC model, the optical spectroscopy data reassemble the determined composition and a connection between disorder signatures and growth conditions is made.