Growth and applications of GeSn-related group-IV semiconductor materials

Zaima, Shigeaki; Nakatsuka, Osamu; Taoka, Noriyuki; Kurosawa, Masashi; Takeuchi, Wakana; Sakashita, Mitsuo

doi:10.1088/1468-6996/16/4/043502

Cited by 168 publications

(114 citation statements)

References 153 publications

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“…Intrinsic bulk Ge is an indirect band-gap material, but it can be converted to a quasi-direct band gap material due to the small separation between the  and L valley (136 meV) [1]. It was shown that the direct band gap of Ge can be realized by tensile strain engineering, alloying with Sn or ultra-high n-type doping [2][3][4][5]. By using only one of these methods it is extremely difficult to achieve a direct band gap.…”

Section: Introductionmentioning

confidence: 99%

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

et al. 2018

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Ge with a quasi-direct band gap can be realized by strain engineering, alloying with Sn or ultra-high n-type doping. In this paper, we use all three approaches together -strain engineering, Sn alloying and n-type doping to fabricate direct band gap GeSn alloys. The heavily-doped n-type GeSn was realized using a CMOS-compatible non-equilibrium material processing. P is used to form a highly-doped n-type GeSn layers and to modify the lattice parameter of GeSn:P alloys. The strain engineering in heavily P-doped GeSn films is confirmed by X-ray diffraction and micro-Raman spectroscopy. The change of the band gap in GeSn:P alloy as a function of P concentration is theoretically predicted using 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 above 1×10 20 cm -3 the band gap renormalization is partially compensated by the Burstein-Moss effect. These results indicate that Ge-based materials have a large potential for the nearinfrared optoelectronic devices, fully compatible with CMOS technology.

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Section: Introductionmentioning

confidence: 99%

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

et al. 2018

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“…GeSn alloy grown by CVD usually shows better uniformity and crystalline quality than that by MBE. 15 Almost all GeSn samples that are capable of obtaining light emission are grown by CVD, including the first photoluminescence (PL) results, 16 the first GeSn laser, 12 etc. On the other hand, for the GeSn alloys with ultra-high Sn contents are grown by MBE.…”

Section: Introductionmentioning

confidence: 99%

Structural properties of GeSn thin films grown by molecular beam epitaxy

et al. 2017

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GeSn thin films on Ge (001) with various Sn concentrations from 3.36 to 7.62% were grown by molecular beam epitaxy and characterized. The structural properties were analyzed by reciprocal space mapping in the symmetric (004) and asymmetric (224) planes by high resolution X-ray diffraction (XRD). The lateral correlation length (LCL) and the mosaic spread (MS) were extracted for the epi-layer peaks in the asymmetric (224) diffraction. With the increase of Sn concentration, the LCL reduces while the MS increases, indicating degrading crystalline quality. Dislocations were observed in the sample with 7.62% Sn concentration by transmission electron microscope, consistent with the strain relaxation found in XRD mapping. Besides, the surface morphologies were investigated.

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“…Recently, there are also some reports on the synthesis of GeSn [21][22][23] and SiGe [20,24,25]. However, there is no experimental report on the synthesis of SnC.…”

Section: Introductionmentioning

confidence: 99%

First principle and tight-binding study of strained SnC

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Moğulkoç

et al. 2017

Journal of Physics and Chemistry of Solids

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We study the electronic and optical properties of strained single-layer SnC in the density functional theory (DFT) and tightbinding models. We extract the hopping parameters tight-binding Hamiltonian for monolayer SnC by considering the DFT results as a reference point. We also examine the phonon spectra in the scheme of DFT, and analyze the bonding character by using Mulliken bond population. Moreover, we show that the band gap modulation and transition from indirect to direct band gap in the compressive strained SnC. The applied tensile strain reduces the band gap and eventually the semiconductor to semimetal transition occurs for 7.5% of tensile strain. In the framework of tight-binding model, the effect of spin-orbit coupling on energy spectrum are also discussed. We indicate that while tensile strain closes the band gap, spin-orbit gap is still present which is order of ∼ 40 meV at the Γ point. The substrate effect is modeled through a staggered sub-lattice potential in the tight-binding approximation. The optical properties of pristine and strained SnC are also examined in the DFT scheme. We present the modulation of real and imaginary parts of dielectric function under applied strain.

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Growth and applications of GeSn-related group-IV semiconductor materials

Cited by 168 publications

References 153 publications

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

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

Structural properties of GeSn thin films grown by molecular beam epitaxy

First principle and tight-binding study of strained SnC

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