scholarly journals Towards a Germanium and Silicon Laser: The History and the Present

Crystals ◽  
2019 ◽  
Vol 9 (12) ◽  
pp. 624
Author(s):  
Ivan Pelant ◽  
Kateřina Kůsová
Keyword(s):  
Quantum Dots ◽  
Band Gap ◽  
Room Temperature ◽  
Light Emitting ◽  
Recent Advances ◽  
The Sixties ◽  
Valence Bands ◽  
Indirect Band Gap ◽  
In The Beginning ◽  
Si Quantum Dots

Various theoretical as well as empirical considerations about how to achieve lasing between the conduction and valence bands in indirect band gap semiconductors (germanium and silicon) are reviewed, starting from the dawn of the laser epoch in the beginning of the sixties. While in Ge the room-temperature lasing under electrical pumping has recently been achieved, in Si this objective remains still illusory. The necessity of applying a slightly different approach in Si as opposed to Ge is stressed. Recent advances in the field are discussed, based in particular on light-emitting Si quantum dots.

Light Emitting Diode with MOS Structures Containing Multiple-Stacked Si Quantum Dots

2007 ◽  
Vol 121-123 ◽  
pp. 557-560 ◽  
Author(s):  
J. Xu ◽  
Katsunori Makihara ◽  
Hidenori Deki ◽  
Yoshihiro Kawaguchi ◽  
Hideki Murakami ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Luminescence Intensity ◽  
Room Temperature ◽  
Light Emission ◽  
Light Emitting Diode ◽  
Infrared Light ◽  
Gate Bias ◽  
Light Emitting ◽  
Mos Structures ◽  
Si Quantum Dots

Light emitting diode with MOS structures containing multiple-stacked Si quantum dots (QDs)/SiO2 was fabricated and the visible-infrared light emission was observed a room temperature when the negative gate bias exceeded the threshold voltage. The luminescence intensity was increased linearly with increasing the injected current density. The possible luminescence mechanism was briefly discussed and the delta P doping was performed to obtain the doped Si QDs and the improvement of EL intensity was demonstrated.

scholarly journals Encapsulated Passivation of Perovskite Quantum Dot (CsPbBr3) Using a Hot-Melt Adhesive (EVA-TPR) for Enhanced Optical Stability and Efficiency

Crystals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 419
Author(s):  
Saradh Prasad ◽  
Mamduh J. Aljaafreh ◽  
Mohamad S. AlSalhi ◽  
Abeer Alshammari
Keyword(s):  
Quantum Dots ◽  
Band Gap ◽  
Surface Defects ◽  
Optoelectronic Devices ◽  
Ethylene Vinyl Acetate ◽  
Light Emitting ◽  
Optical Stability ◽  
Perovskite Quantum Dots ◽  
Polymer Light Emitting Diodes ◽  
Hot Melt

The notable photophysical characteristics of perovskite quantum dots (PQDs) (CsPbBr3) are suitable for optoelectronic devices. However, the performance of PQDs is unstable because of their surface defects. One way to address the instability is to passivate PQDs using different organic (polymers, oligomers, and dendrimers) or inorganic (ZnS, PbS) materials. In this study, we performed steady-state spectroscopic investigations to measure the photoluminescence (PL), absorption (A), transmission (T), and reflectance (R) of perovskite quantum dots (CsPbBr3) and ethylene vinyl acetate/terpene phenol (1%) (EVA-TPR (1%), or EVA) copolymer/perovskite composites in thin films with a thickness of 352 ± 5 nm. EVA is highly transparent because of its large band gap; furthermore, it is inexpensive and easy to process. However, the compatibility between PQDs and EVA should be established; therefore, a series of analyses was performed to compute parameters, such as the band gap, the coefficients of absorbance and extinction, the index of refractivity, and the dielectric constant (real and imaginary parts), from the data obtained from the above investigation. Finally, the optical conductivities of the films were studied. All these analyses showed that the EVA/PQDs were more efficient and stable both physically and optically. Hence, EVA/PQDs could become copolymer/perovskite active materials suitable for optoelectronic devices, such as solar cells and perovskite/polymer light-emitting diodes (PPLEDs).

Room temperature synthesis of Sn2+ doped highly luminescent CsPbBr3 quantum dots for high CRI white light-emitting diodes

Nanoscale ◽  
2021 ◽  
Author(s):  
Dongdong Yan ◽  
Qionghua Mo ◽  
Shuangyi Zhao ◽  
Wensi Cai ◽  
Zhigang Zang
Keyword(s):  
Quantum Dots ◽  
Quantum Yield ◽  
White Light ◽  
Room Temperature ◽  
Temperature Synthesis ◽  
Light Emitting ◽  
Photoluminescence Quantum Yield ◽  
Hot Injection ◽  
White Light Emitting Diodes ◽  
Cspbbr3 Quantum Dots

With a high photoluminescence quantum yield (PLQY) being able to exceed 90% for those prepared by hot injection method, CsPbBr3 quantum dots (QDs) have attracted intensive attentions for white light-emitting...

scholarly journals Temperature-dependent optical and vibrational properties of PtSe2 thin films

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Desman P. Gulo ◽  
Han Yeh ◽  
Wen-Hao Chang ◽  
Hsiang-Lin Liu
Keyword(s):  
Thin Films ◽  
Band Gap ◽  
Room Temperature ◽  
Near Infrared ◽  
Technological Development ◽  
Phonon Modes ◽  
Research Attention ◽  
Practical Applications ◽  
Infrared Frequency Range ◽  
Indirect Band Gap

Abstract PtSe2 has received substantial research attention because of its intriguing physical properties and potential practical applications. In this paper, we investigated the optical properties of bilayer and multilayer PtSe2 thin films through spectroscopic ellipsometry over a spectral range of 0.73–6.42 eV and at temperatures between 4.5 and 500 K. At room temperature, the spectra of refractive index exhibited several anomalous dispersion features below 1000 nm and approached a constant value in the near-infrared frequency range. The thermo-optic coefficients of bilayer and multilayer PtSe2 thin films were (4.31 ± 0.04) × 10−4/K and (–9.20 ± 0.03) × 10−4/K at a wavelength of 1200 nm. Analysis of the optical absorption spectrum at room temperature confirmed that bilayer PtSe2 thin films had an indirect band gap of approximately 0.75 ± 0.01 eV, whereas multilayer PtSe2 thin films exhibited semimetal behavior. The band gap of bilayer PtSe2 thin films increased to 0.83 ± 0.01 eV at 4.5 K because of the suppression of electron–phonon interactions. Furthermore, the frequency shifts of Raman-active Eg and A1g phonon modes of both thin films in the temperature range between 10 and 500 K accorded with the predictions of the anharmonic model. These results provide basic information for the technological development of PtSe2-based optoelectronic and photonic devices at various temperatures.

scholarly journals Quantum Dots and Applications

Materials ◽  
2020 ◽  
Vol 13 (4) ◽  
pp. 897
Author(s):  
Chang-Yeol Han ◽  
Hyun-Sik Kim ◽  
Heesun Yang
Keyword(s):  
Quantum Dots ◽  
Optical Properties ◽  
Band Gap ◽  
Light Emitting Diodes ◽  
Photovoltaic Cells ◽  
Core Shell ◽  
Special Issue ◽  
High Quality ◽  
Light Emitting ◽  
Size Dependent

It is the unique size-dependent band gap of quantum dots (QDs) that makes them so special in various applications. They have attracted great interest, especially in optoelectronic fields such as light emitting diodes and photovoltaic cells, because their photoluminescent characteristics can be significantly improved via optimization of the processes by which they are synthesized. Control of their core/shell heterostructures is especially important and advantageous. However, a few challenges remain to be overcome before QD-based devices can completely replace current optoelectronic technology. This Special Issue provides detailed guides for synthesis of high-quality QDs and their applications. In terms of fabricating devices, tailoring optical properties of QDs and engineering defects in QD-related interfaces for higher performance remain important issues to be addressed.

Recent advances in white light-emitting diodes of carbon quantum dots

Nanoscale ◽  
2020 ◽  
Vol 12 (8) ◽  
pp. 4826-4832 ◽  
Author(s):  
Ping He ◽  
Yuxin Shi ◽  
Ting Meng ◽  
Ting Yuan ◽  
Yunchao Li ◽  
...  
Keyword(s):  
Quantum Dots ◽  
White Light ◽  
High Performance ◽  
Light Emitting Diodes ◽  
Carbon Quantum Dots ◽  
Single Component ◽  
Light Emitting ◽  
Recent Advances ◽  
White Light Emitting Diodes

In this mini review, we update the latest research in the design of high-performance WLEDs with different correlated color temperatures by tuning the red component using red emissive CQDs and single-component white emissive CQDs.

An Ultra-Simple Method for Synthesis of Violet CdS Quantum Dots at Sub-Room Temperature

2020 ◽  
Vol 20 (6) ◽  
pp. 3935-3938 ◽  
Author(s):  
Chandan Yadav ◽  
Karan Surana ◽  
Pramod K. Singh ◽  
Bhaskar Bhattacharya
Keyword(s):  
Quantum Dots ◽  
Room Temperature ◽  
Uv Light ◽  
Xrd Analysis ◽  
Wet Chemical Method ◽  
Simple Method ◽  
Light Emitting ◽  
Violet Color ◽  
Wet Chemical ◽  
Sensitized Solar Cells

The emergence of fluorescence quantum dots (QDs) has led to the development of variety of applications in science and technology. Owing to the diverse optical and electrical properties of CdS QDs we have synthesized the same using wet chemical method. The QDs have been prepared at sub-room temperature using a new solvent comprising a mixture of water and methanol. The QDs when seen under UV light radiate violet color. The band-gap of the QDs deduced from the absorption spectra was 3.08 eV while PL spectra of the QDs suggested possibility of multiple exciton generation with a close to narrow size distribution. XRD analysis confirmed cubic structure of the particles. The obtained results suggest that these QDs can play ideal role in quantum dot sensitized solar cells (QDSSC) or in light emitting diodes (LEDs).

scholarly journals Direct-Current and Alternating-Current Driving Si Quantum Dots-Based Light Emitting Device

2014 ◽  
Vol 20 (4) ◽  
pp. 206-211 ◽  
Author(s):  
Weiwei Mu ◽  
Pei Zhang ◽  
Jun Xu ◽  
Shenghua Sun ◽  
Jie Xu ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Direct Current ◽  
Alternating Current ◽  
Light Emitting ◽  
Si Quantum Dots
Sign in / Sign up

Export Citation Format

Share Document