Regensburg 2019 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 8: Transport and theory of electronic structure

HL 8.9: Vortrag

Montag, 1. April 2019, 17:00–17:15, H33

Ab-initio electronic structure calculations for random alloys: Accurate SiGe composition-dependent band gap at reduced computational cost — •Petr A. Khomyakov, Daniele Stradi, Ulrik G. Vej-Hansen, Maeng-Eun Lee, Jess Wellendorff, Søren Smidstrup, and Kurt Stokbro — Synopsys QuantumATK, Fruebjergvej 3, 2100 Copenhagen, Denmark

Semiconductor random alloys are commonly used in microelectronics, so first-principles calculations for the physical properties of random alloys are of great interest. This kind of calculations allow for obtaining the physical parameters for any alloy composition. However, configuration sampling of results for alloy supercells, which is the standard approach to capturing the effect of alloy disorder on the physical properties, can be computationally demanding.

In this study, we use the special quasi-random structures (SQS) approach for modeling SiGe random alloys over the entire range of alloy compositions. The SQS method alleviates the need for configuration sampling, reducing the computational cost considerably. At each alloy composition, we apply our recently-developed pseudopotential projector-shift (PPS) method for obtaining accurate band energies for silicon and germanium within the framework of the DFT-PBE functional approach. Using the SQS + PPS-PBE combination allowed us to obtain accurate SiGe band gaps across the entire range of alloy compositions, as compared to room-temperature measured gaps. Applying the HSE06 hybrid functional yields the composition-dependent SiGe band gaps in good agreement with low-temperature measured gaps.

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