scholarly journals In-Situ Annealing and Hydrogen Irradiation of Defect-Enhanced Germanium Quantum Dot Light Sources on Silicon

Crystals ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 351
Author(s):  
Lukas Spindlberger ◽  
Johannes Aberl ◽  
Antonio Polimeni ◽  
Jeffrey Schuster ◽  
Julian Hörschläger ◽  
...  
Keyword(s):  
Room Temperature ◽  
Proton Irradiation ◽  
Light Emission ◽  
Bulk Diffusion ◽  
Group Iv ◽  
Ex Situ ◽  
Light Sources ◽  
Emission Properties ◽  
Pl Emission

While light-emitting nanostructures composed of group-IV materials fulfil the mandatory compatibility with CMOS-fabrication methods, factors such as the structural stability of the nanostructures upon thermal annealing, and the ensuing photoluminescence (PL) emission properties, are of key relevance. In addition, the possibility of improving the PL efficiency by suitable post-growth treatments, such as hydrogen irradiation, is important too. We address these issues for self-assembled Ge quantum dots (QDs) that are co-implanted with Ge ions during their epitaxial growth. The presence of defects introduced by the impinging Ge ions results in pronounced PL-emission at telecom wavelengths up to room temperature (RT) and above. This approach allows us to overcome the severe limitations of light generation in the indirect-band-gap group-IV materials. By performing in-situ annealing, we demonstrate a high PL-stability of the defect-enhanced QD (DEQD) system against thermal treatment up to 600 °C for at least 2 h, even though the Ge QDs are structurally affected by Si/Ge intermixing via bulk diffusion. The latter, in turn, allows for emission tuning of the DEQDs over the entire telecom wavelength range from 1.3 µm to 1.55 µm. Two quenching mechanisms for light-emission are discussed; first, luminescence quenching at high PL recording temperatures, associated with the thermal escape of holes to the surrounding wetting layer; and second, annealing-induced PL-quenching at annealing temperatures >650 °C, which is associated with a migration of the defect complex out of the QD. We show that low-energy ex-situ proton irradiation into the Si matrix further improves the light emission properties of the DEQDs, whereas proton irradiation-related optically active G-centers do not affect the room temperature luminescence properties of DEQDs.

scholarly journals The Deformation Behavior and Bending Emissions of ZnO Microwire Affected by Deformation-Induced Defects and Thermal Tunneling Effect

Sensors ◽  
2021 ◽  
Vol 21 (17) ◽  
pp. 5887
Author(s):  
Linlin Shi ◽  
Hong Wang ◽  
Xiaohui Ma ◽  
Yunpeng Wang ◽  
Fei Wang ◽  
...  
Keyword(s):  
Room Temperature ◽  
Luminescent Properties ◽  
Tunneling Effect ◽  
Light Sources ◽  
Electrical Characteristics ◽  
Fundamental Research ◽  
Induced Defects ◽  
Theoretical Simulations ◽  
Bright Emission

The realization of electrically pumped emitters at micro and nanoscale, especially with flexibility or special shapes is still a goal for prospective fundamental research and application. Herein, zinc oxide (ZnO) microwires were produced to investigate the luminescent properties affected by stress. To exploit the initial stress, room temperature in situ elastic bending stress was applied on the microwires by squeezing between the two approaching electrodes. A novel unrecoverable deformation phenomenon was observed by applying a large enough voltage, resulting in the formation of additional defects at bent regions. The electrical characteristics of the microwire changed with the applied bending deformation due to the introduction of defects by stress. When the injection current exceeded certain values, bright emission was observed at bent regions, ZnO microwires showed illumination at the bent region priority to straight region. The bent emission can be attributed to the effect of thermal tunneling electroluminescence appeared primarily at bent regions. The physical mechanism of the observed thermoluminescence phenomena was analyzed using theoretical simulations. The realization of electrically induced deformation and the related bending emissions in single microwires shows the possibility to fabricate special-shaped light sources and offer a method to develop photoelectronic devices.

scholarly journals The Structural, Electronic, and Optical Properties of Ge/Si Quantum Wells: Lasing at a Wavelength of 1550 nm

Nanomaterials ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 1006
Author(s):  
Hongqiang Li ◽  
Jianing Wang ◽  
Jinjun Bai ◽  
Shanshan Zhang ◽  
Sai Zhang ◽  
...  
Keyword(s):  
Optical Properties ◽  
Quantum Wells ◽  
Room Temperature ◽  
Light Emission ◽  
Single Mode ◽  
Group Iv ◽  
Light Power ◽  
Fully Integrated ◽  
Electronic And Optical Properties ◽  
Novel Approach

The realization of a fully integrated group IV electrically driven laser at room temperature is an essential issue to be solved. We introduced a novel group IV side-emitting laser at a wavelength of 1550 nm based on a 3-layer Ge/Si quantum well (QW). By designing this scheme, we showed that the structural, electronic, and optical properties are excited for lasing at 1550 nm. The preliminary results show that the device can produce a good light spot shape convenient for direct coupling with the waveguide and single-mode light emission. The laser luminous power can reach up to 2.32 mW at a wavelength of 1550 nm with a 300-mA current. Moreover, at room temperature (300 K), the laser can maintain maximum light power and an ideal wavelength (1550 nm). Thus, this study provides a novel approach to reliable, efficient electrically pumped silicon-based lasers.

scholarly journals Ion-Irradiation-Induced Amorphization Of Cadmium Niobate Pyrochlore

2000 ◽  
Vol 650 ◽  
Author(s):  
A. Meldrum ◽  
K. Beaty ◽  
L. A. Boatner ◽  
C. W. White
Keyword(s):  
Electron Microscope ◽  
Ambient Temperature ◽  
Transmission Electron Microscope ◽  
Room Temperature ◽  
Ion Irradiation ◽  
Ex Situ ◽  
Temperature Dependent ◽  
Transmission Electron ◽  
Ion Energies

ABSTRACTIrradiation-induced amorphization of Cd2Nb2O7 pyrochlore was investigated by means of in-situ temperature-dependent ion-irradiation experiments in a transmission electron microscope, combined with ex-situ ion-implantation (at ambient temperature) and RBS/channeling analysis. The in-situ experiments were performed using Ne or Xe ions with energies of 280 and 1200 keV, respectively. For the bulk implantation experiments, the incident ion energies were 70 keV (Ne+) and 320 keV (Xe2+). The critical amorphization temperature for Cd2Nb2O7 is ∼480 K (280 keV Ne+) or ∼620 K (1200 keV Xe2+). The dose for in-situ amorphization at room temperature is 0.22 dpa for Xe2+, but is 0.65 dpa for Ne+ irradiation. Both types of experiments suggest a cascade overlap mechanism of amorphization. The results were analyzed in light of available models for the crystalline-to-amorphous transformation and were compared to previous ionirradiation experiments on other pyrochlore compositions.

Phase Transformations in Sol-Gel PZT Thin Films

2000 ◽  
Vol 623 ◽  
Author(s):  
D.P. Eakin ◽  
M.G. Norton ◽  
D.F. Bahr
Keyword(s):  
Thin Films ◽  
Heat Treatment ◽  
Room Temperature ◽  
Structural Changes ◽  
Sol Gel ◽  
Ex Situ ◽  
Ambient Conditions ◽  
Crystalline Films ◽  
In Situ Heating

AbstractThin films of PZT were deposited onto platinized and bare single crystal NaCl using spin coating and sol-gel precursors. These films were then analyzed using in situ heating in a transmission electron microscope. The results of in situ heating are compared with those of an ex situ heat treatment in a standard furnace, mimicking the heat treatment given to entire wafers of these materials for use in MEMS and ferroelectric applications. Films are shown to transform from amorphous to nanocrystalline over the course of days when held at room temperature. While chemical variations are found between films crystallized in ambient conditions and films crystallized in the vacuum conditions of the microscope, the resulting crystal structures appear to be insensitive to these differences. Significant changes in crystal structure are found at 500°C, primarily the change from largely amorphous to the beginnings of clearly crystalline films. Crystallization does occur over the course of weeks at room temperature in these films. Structural changes are more modest in these films when heated in the TEM then those observed on actual wafers. The presence of Pt significantly influences both the resulting structure and morphology in both in situ and ex situ heated films. Without Pt present, the films appear to form small, 10 nm grains consisting of both cubic and tetragonal phases, whereas in the case of the Pt larger, 100 nm grains of a tetragonal phase are formed.

The Enabling Role of Surface Passivation in Visible Photoluminescence from Si Nanoparticles

1993 ◽  
Vol 318 ◽  
Author(s):  
A.A. Seraphin ◽  
E. Werwa ◽  
L.A. Chiu ◽  
K.D. Kolenbrander
Keyword(s):  
Room Temperature ◽  
Surface Passivation ◽  
Light Emission ◽  
Supersonic Expansion ◽  
Expansion Technique ◽  
Si Nanoparticles ◽  
Silicon Nanocrystallites ◽  
Pl Emission ◽  
Si Nanocrystallites

ABSTRACTSilicon nanocrystallites have been studied in a variety of passivating environments to study the role of surface passivation in visible light emission from the particles. Thin films of Si nanocrystallites have been deposited by a laser ablation supersonic expansion technique. The films show significant room temperature photoluminescence (PL) behavior only after processing to achieve surface passivation. Passivation effects on light emission are studied through PL emission spectroscopy on clusters in the gas phase, as well as films in a variety of passivating media. The intensity of PL emission seems to scale with the extent of surface passivation, but the specific nature of the passivating species is not critical in defining the wavelength of emitted light.

Characterization of GaAs and Ge Films on (100) Silicon

1987 ◽  
Vol 91 ◽  
Author(s):  
J.-M. Baribeau ◽  
D.C. Houghton ◽  
P. MaignÉ ◽  
W.T. Moore ◽  
R.L.S. Devine ◽  
...  
Keyword(s):  
Surface Preparation ◽  
Group Iv ◽  
Ex Situ ◽  
Rapid Thermal Anneal ◽  
Defect Reduction ◽  
Group Iii ◽  
Superlattice Dislocation ◽  
Strained Layer Superlattice

ABSTRACTA UHV MBE apparatus in which the deposition of both group IV and group III-V components is possible without breaking vacuum has been utilized to compare the growth of GaAs epilayers on non-polar Si(100) and Ge coated Si(100) substrates. In addition, a comparison of GaAs epilayers grown on substrates cleaned by ex-situ techniques and on substrates given all UHV in-situ surface preparation was made. Defect reduction by the incorporation of strained-layer superlattice dislocation filters and by post-growth rapid thermal anneal (RTA) thermal cycles was also investigated. Optical and material properties comparable to MBE grown GaAs/GaAs were obtained for GaAs grown on Ge coated Si(100) substrates.

Well Thickness And Doping Effects, And Room Temperature emission mechanisms in InGaN/GaN And GaN/AlGaN Multiple Quantum Wells

1997 ◽  
Vol 482 ◽  
Author(s):  
K. C. Zeng ◽  
M. Smith ◽  
J. Y. Lin ◽  
H. X. Jiang ◽  
H. Tang ◽  
...  
Keyword(s):  
Quantum Wells ◽  
Room Temperature ◽  
Multiple Quantum Wells ◽  
Multiple Quantum ◽  
Emission Properties ◽  
Si Doping ◽  
Doping Effects ◽  
Pl Emission

AbstractEffects of well thickness and Si-doping on the photoluminescence (PL) emission properties of GaN/AlxGa1-xN (x ∼ 0.07) and InxGa1-xN/GaN (x ∼ 0.15–0.2) multiple quantum wells (MQWs) grown both by MOCVD and reactive MBE have been studied. The room temperature emission mechanisms have also been addressed.

Visible Light Emission from Porous Silicon Examined by Photoluminescence and Raman Spectroscopy

1992 ◽  
Vol 283 ◽  
Author(s):  
Terry R. Guilinger ◽  
Michael J. Kelly ◽  
David R. Tallant ◽  
David A. Redman ◽  
David M. Follstaedt
Keyword(s):  
Porous Silicon ◽  
Visible Light ◽  
Hydrofluoric Acid ◽  
Light Emission ◽  
Fold Increase ◽  
Blue Shift ◽  
Ex Situ ◽  
Pl Spectra ◽  
Light Spectra

ABSTRACTWe describe the acquisition of Raman and photoluminescence (PL) spectra on porous silicon (PS) samples that emit visible light. Spectra were acquired in both ex situ experiments (after exposure to air) and in situ experiments (with the PS covered either with the hydrofluoric acid electrolyte used in the formation process or water). Our results generally show a correlation of blue-shifted PL with increased oxidation. In one set of ex situ experiments, however, we observed an inconsistency in the shift of the wavelengthof maximum luminescence intensity for PS samples that exhibit oxygenated character in the Raman spectra. A higher anodization current density produced a red shift in the PL spectra in one experiment, while chemical dissolution of the PS by hydrofluoric acid produced the well-known blue shift in the other case. In two in situ experiments, we observed very weak and red-shifted PL for a PS sample immersed in HF (compared to the same sample measured later in air) while in another we immersed air-exposed PS in water and observed a 15-fold increase in PL intensity along with a blue shift in the luminescence maximum.

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