Carrier recombination in tailored multilayer Si/Si1−xGex nanostructures

Mala, Selina A.; Tsybeskov, L.; Lockwood, D. J.; Wu, Xiaohua; Baribeau, J.‐M.

doi:10.1016/j.physb.2014.03.084

Cited by 6 publications

(17 citation statements)

References 22 publications

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“…The intensity of the 0.92 eV PL peak is linearly dependent on the excitation energy density with no saturation evident until an energy density of at least ~50 mJ/cm 2 , while the 0.8 eV PL peak intensity varies with excitation energy density as the square root (Mala et al, 2014). Also, the rise time of this latter PL peak decreases with both increasing excitation energy density and temperature.…”

Section: Single Nanometer-thick Sige Quantum Well Samplementioning

confidence: 94%

“…The PL excited at 532 nm and recorded at 0.78 eV, which originates predominantly from the lowermost Si/SiGe cluster layers, has a lifetime that is approximately 100 times longer than the same Cw excitation with the indicated excitation wavelengths and (B) pulsed 355-nm excitation using the time-integrated and peakintensity methods (Mala et al, 2014).…”

Section: Photoluminescence From Sige Nanostructuresmentioning

confidence: 99%

“…Indeed, the underlying physical mechanism involved in non-exponential PL decay has yet to be FiGURe 17 | Carrier recombination rates (dots) extracted from the experimental data as a function of the distance between electrons and holes for photon detection energies associated with SiGe NL PL (~ 0.92 ev) and SiGe cluster PL (~ 0.8 ev). The solid line is the theoretically calculated electron-hole recombination rate (Mala et al, 2014 identified. In a different approach to this issue, we extract the recombination rate directly from the PL decays without requiring any assumption or a specific physical model.…”

Section: Interpretation Based On Interfacial Recombinationmentioning

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: Single Nanometer-thick Sige Quantum Well Samplementioning

confidence: 94%

Section: Photoluminescence From Sige Nanostructuresmentioning

confidence: 99%

Section: Interpretation Based On Interfacial Recombinationmentioning

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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“…An overview of earlier work on light emission from SiGe nanostructures in general, including quantum wells, wires, and dots, has been given elsewhere (21). Here, we provide an overview of recent continuous-wave (CW) and time-resolved photoluminescence investigations of the recombination dynamics of three-dimensional (3D) Si/Si1-xGex multilayer nanostructures grown by MBE (9,10). The measurements were performed on Si/Si1-xGex nanostructures where a single Si1-xGex nanometer-thick layer (NL) is incorporated into Si/Si0.6Ge0.4 3D-cluster multilayer (CM) structures.…”

Section: Three-dimensional Sige Nanostructuresmentioning

confidence: 99%

“…The latter structure is based on constructing a new super unit cell comprised of multiple planar epitaxial layers of Si and Ge grown on (001) Si0.4Ge0.6 (8). Others are based on silicon-germanium layers grown epitaxially on silicon in such a way as to form multiple layer three-dimensional nanostructures (quantum dots) (9,10). A simple and efficient electrochemical process that combines galvanic reaction and focused-ion-beam lithography to selectively synthesize gold nanoparticles has been developed that can used to grow ordered SiGe nanowire arrays with a predefined diameter (200 nm) and position (11,12).…”

Section: Introductionmentioning

confidence: 99%

Progress in Light Emission from Silicon and Germanium Nanostructures

Lockwood

2018

ECS Trans.

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(Invited) Bright Light Emitting Silicon/Germanium Nanostructures

Lockwood

2015

ECS Trans.

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Light emission from Si nanostructures has been of great interest for some time now owing to the need for silicon-based light sources for applications in silicon opto-electronics and photonics. Both Si and Ge possess indirect band gaps, which makes them very inefficient light emitters. Band gap engineering employing quantum wells or quantum dots has been proposed as one way to overcome this limitation and Si/Ge or Si/SiGe-alloy thin-multilayer nanostructures grown on Si have been produced on this principle, and although light emission with greatly improved efficiency has been obtained at low temperatures the emission at room temperature is still very weak, because of exciton dissociation. Recent advances in band gap engineering technology have resulted in the development of new systems incorporating one-, two-, and three-dimensionally confined Si-Ge nanostructures that produce bright light in the near infrared. Here, the novel optical properties of three such nanostructures – super unit cells, nanowires, and nanocluster layers – are explored.

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Carrier recombination in tailored multilayer Si/Si1−xGex nanostructures

Cited by 6 publications

References 22 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

Progress in Light Emission from Silicon and Germanium Nanostructures

(Invited) Bright Light Emitting Silicon/Germanium Nanostructures

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