Structural and optical properties of axial silicon-germanium nanowire heterojunctions

Wang, Sheldon; Tsybeskov, L.; Kamins, Theodore I.; Wu, Xiaohua; Lockwood, D. J.

doi:10.1063/1.4937345

Cited by 12 publications

(19 citation statements)

References 49 publications

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“…The temperature increase produces a strong shift of the Raman peak associated with the Si-Si(Ge) vibration mode toward higher wavenumbers, indicating strong (2-3 GPa) compressive strain, as also found from the PL data. This conclusion is supported by the Raman polarization dependence in Si/Ge axial NW HJs (Wang et al, 2015).…”

Section: Si Gesupporting

confidence: 73%

“…Figure 7A shows Raman spectra of Si/Ge NW HJs measured using lasers with different wavelengths. Under 515 nm excitation, we observe three distinct Raman peaks associated with the Si-Si (~520 cm (Wang et al, 2015). Note that the second Raman peak around 270 cm −1 under 458 nm excitation is, most likely, associated with a laser plasma line.…”

Section: Si Gementioning

confidence: 82%

“…Thus, investigations of axial Si/Ge NW HJs can open new and interesting prospects for constructing low defect-density NSs for applications in CMOS compatible photonic components. We have investigated such axial structures and summarize our findings below (Wang et al, 2015).…”

Section: Quantum Wiresmentioning

confidence: 99%

“…These structural imperfections are located within a 2-3-nm-thick interface layer between the NW core and an oxide layer at the NW surface and they are slightly extended (up to The PL spectra of the Si/Ge NW HJs at various (marked) temperatures. The PL spectra peak shift with temperature increase is indicated by dashed lines (Wang et al, 2015).…”

Section: Si Gementioning

confidence: 99%

“…An amorphous layer of ~ 1 nm thickness at the NW surface is indicated by an arrow (Wang et al, 2015). energy-dispersive X-ray spectrometer (EDX) with a probe size of 0.2 nm, Raman scattering spectroscopy, and PL spectroscopy.…”

Section: Si Gementioning

confidence: 99%

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Si/SiGe Heterointerfaces in One-, Two-, and Three-Dimensional Nanostructures: Their Impact on SiGe Light Emission

Lockwood

Baribeau

et al. 2016

Front. Mater.

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Fast optical interconnects together with an associated light emitter that are both compatible with conventional Si-based complementary metal-oxide-semiconductor (CMOS) integrated circuit technology is an unavoidable requirement for the next-generation microprocessors and computers. Self-assembled Si/Si1−xGex nanostructures (NSs), which can emit light at wavelengths within the important optical communication wavelength range of 1.3-1.55 μm, are already compatible with standard CMOS practices. However, the expected long carrier radiative lifetimes observed to date in Si and Si/Si1−xGex NSs have prevented the attainment of efficient light-emitting devices, including the desired lasers. Thus, the engineering of Si/ Si1−xGex heterostructures having a controlled composition and sharp interfaces is crucial for producing the requisite fast and efficient photoluminescence (PL) at energies in the range of 0.8-0.9 eV. In this paper, we assess how the nature of the interfaces between SiGe NSs and Si in heterostructures strongly affects carrier mobility and recombination for physical confinement in three dimensions (corresponding to the case of quantum dots), two dimensions (corresponding to quantum wires), and one dimension (corresponding to quantum wells). The interface sharpness is influenced by many factors, such as growth conditions, strain, and thermal processing, which in practice can make it difficult to attain the ideal structures required. This is certainly the case for NS confinement in one dimension. However, we demonstrate that axial Si/Ge nanowire (NW) heterojunctions (HJs) with a Si/ Ge NW diameter in the range 50-120 nm produce a clear PL signal associated with bandto-band electron-hole recombination at the NW HJ that is attributed to a specific interfacial SiGe alloy composition. For three-dimensional confinement, the experiments outlined here show that two quite different Si1−xGex NSs incorporated into a Si0.6Ge0.4 wavy superlattice structure display PL of high intensity while exhibiting a characteristic decay time that is up to 1000 times shorter than that found in conventional Si/SiGe NSs. The non-exponential PL decay found experimentally in Si/SiGe NSs can be interpreted as resulting from variations in the separation distance between electrons and holes at the Si/SiGe heterointerface. The results demonstrate that a sharp Si/SiGe heterointerface acts to reduce the carrier radiative recombination lifetime and increase the PL quantum efficiency, which makes these SiGe NSs favorable candidates for future light-emitting device applications in CMOS technology.

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Section: Si Gesupporting

confidence: 73%

Section: Si Gementioning

confidence: 82%

Section: Quantum Wiresmentioning

confidence: 99%

Section: Si Gementioning

confidence: 99%

Section: Si Gementioning

confidence: 99%

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Si/SiGe Heterointerfaces in One-, Two-, and Three-Dimensional Nanostructures: Their Impact on SiGe Light Emission

Lockwood

Baribeau

et al. 2016

Front. Mater.

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Hetero structure PNPN tunnel FET: Analysis of scaling effects on counter doping

Joseph

Singh

Hariharan

et al. 2018

Applied Surface Science

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Low-Temperature Growth of Axial Si/Ge Nanowire Heterostructures Enabled by Trisilane

et al. 2017

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Axial Si/Ge heterostructure nanowires, despite their promise in applications ranging from electronics to thermal transport, remain notoriously difficult to synthesize. Here, we grow axial Si/Ge heterostructures at low temperature using a Au catalyst with a combination of trisilane and digermane. This approach yields, as determined with detailed electron microscopy characterization, arrays of epitaxial Si/Ge nanowires with excellent morphologies and purely axial composition profiles. Our data indicates that heterostructure formation can occur via either the vapor-liquid-solid (VLS) or vapor-solid-solid (VSS) mechanisms. These findings highlight the importance of precursor chemistry on semiconductor nanowire synthesis and open the door to Si/Ge nanowires with programmable quantum domains.

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Structural and optical properties of axial silicon-germanium nanowire heterojunctions

Cited by 12 publications

References 49 publications

Si/SiGe Heterointerfaces in One-, Two-, and Three-Dimensional Nanostructures: Their Impact on SiGe Light Emission

Si/SiGe Heterointerfaces in One-, Two-, and Three-Dimensional Nanostructures: Their Impact on SiGe Light Emission

Hetero structure PNPN tunnel FET: Analysis of scaling effects on counter doping

Low-Temperature Growth of Axial Si/Ge Nanowire Heterostructures Enabled by Trisilane

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