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arXiv · 1901.01721

Strain and Band-Gap Engineering in Ge-Sn Alloys via P Doping

Slawomir Prucnal·Yonder Berencén·Mao Wang·Jörg Grenzer·Matthias Voelskow·Rene Hübner·Yuji Yamamoto·Alexander Scheit·Florian Bärwolf·Vitaly Zviagin·Rüdiger Schmidt-Grund·Marius Grundmann·Jerzy Żuk·Marcin Turek·Andrzej Droździel·Krzysztof Pyszniak·Robert Kudrawiec·Maciej P. Polak·Lars Rebohle·Wolfgang Skorupa·Manfred Helm·Shengqiang Zhou
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Abstract

Ge with a quasi-direct band gap can be realized by strain engineering, alloying with Sn, or ultrahigh n-type doping. In this work, we use all three approaches together to fabricate direct-band-gap Ge-Sn alloys. The heavily doped n-type Ge-Sn is realized with CMOS-compatible nonequilibrium material processing. P is used to form highly doped n-type Ge-Sn layers and to modify the lattice parameter of P-doped Ge-Sn alloys. The strain engineering in heavily-P-doped Ge-Sn films is confirmed by x-ray diffraction and micro Raman spectroscopy. The change of the band gap in P-doped Ge-Sn alloy as a function of P concentration is theoretically predicted by density functional theory and experimentally verified by near-infrared spectroscopic ellipsometry. According to the shift of the absorption edge, it is shown that for an electron concentration greater than 1x10^20 cm-3 the band-gap renormalization is partially compensated by the Burstein-Moss effect. These results indicate that Ge-based materials have high potential for use in near-infrared optoelectronic devices, fully compatible with CMOS technology.

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Slawomir Prucnal, Yonder Berencén, Mao Wang, Jörg Grenzer, Matthias Voelskow, Rene Hübner, Yuji Yamamoto, Alexander Scheit, Florian Bärwolf, Vitaly Zviagin, Rüdiger Schmidt-Grund, Marius Grundmann, Jerzy Żuk, Marcin Turek, Andrzej Droździel, Krzysztof Pyszniak, Robert Kudrawiec, Maciej P. Polak, Lars Rebohle, Wolfgang Skorupa, Manfred Helm, Shengqiang Zhou. 2019-01-07. Strain and Band-Gap Engineering in Ge-Sn Alloys via P Doping. https://doi.org/10.1103/physrevapplied.10.064055

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